研究者データベース

小野田 晃(オノダ アキラ)
地球環境科学研究院 物質機能科学部門 生体物質科学分野
教授

基本情報

所属

  • 地球環境科学研究院 物質機能科学部門 生体物質科学分野

職名

  • 教授

学位

  • 博士(理学)(2002年03月 大阪大学)

ホームページURL

科研費研究者番号

  • 60366424

J-Global ID

研究キーワード

  • ケミカルバイオロジー   ナノバイオテクノロジー   高分子錯体化学   生物無機化学   生体機能関連化学   Chemical Biology   Nanobio Research   Bioinorganic Chemistry   

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 電子デバイス、電子機器
  • ナノテク・材料 / 生体化学
  • ナノテク・材料 / 無機・錯体化学

学歴

  •         - 2002年03月   大阪大学   大学院理学研究科
  •         - 1999年   大阪大学   理学研究科   高分子科学

所属学協会

  • 錯体化学会   アメリカ化学会   高分子学会   日本化学会   

研究活動情報

論文

  • Koki Matsumoto, Akira Onoda, Tomoyuki Kitano, Takao Sakata, Hidehiro Yasuda, Stéphane Campidelli, Takashi Hayashi
    ACS Applied Materials and Interfaces 13 13 15101 - 15112 2021年04月 [査読有り]
     
    Pyrolytically prepared iron and nitrogen codoped carbon (Fe/N/C) catalysts are promising nonprecious metal electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell applications. Fabrication of the Fe/N/C catalysts with Fe-Nx active sites having precise structures is now required. We developed a strategy for thermally controlled construction of the Fe-Nx structure in Fe/N/C catalysts by applying a bottom-up synthetic methodology based on a N-doped graphene nanoribbon (N-GNR). The preorganized aromatic rings within the precursors assist graphitization during generation of the N-GNR structure with iron-coordinating sites. The Fe/N/C catalyst prepared from the N-GNR precursor, iron ion, and the carbon support Vulcan XC-72R provides a high onset potential of 0.88 V (vs reversible hydrogen electrode (RHE)) and promotes efficient four-electron ORR. X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) studies reveal that the N-GNR precursor induces the formation of iron-coordinating nitrogen species during pyrolysis. The details of the graphitization process of the precursor were further investigated by analyzing the precursors pyrolyzed at various temperatures using MgO particles as a sacrificial template, with the results indicating that the graphitized structure was obtained at 700 °C. The preorganized N-GNR precursors and its pyrolysis conditions for graphitization are found to be important factors for generation of the Fe-Nx active sites along with the N-GNR structure in high-performance Fe/N/C catalysts for the ORR.
  • Shunsuke Kato, Akira Onoda, Alexander R. Grimm, Ulrich Schwaneberg, Takashi Hayashi
    Journal of Inorganic Biochemistry 216 2021年03月 [査読有り]
     
    A whole-cell biohybrid catalyst where a (pentamethylcyclopentadienyl)rhodium(III) (Cp*Rh(III)) complex was covalently incorporated into the cavity of nitrobindin (NB), a β-barrel protein, was prepared on an E. coli cell surface to produce isoquinolines via C(sp2)–H bond activation. In this whole-cell biohybrid system, the Cp*Rh(III)-dithiophosphate complex with latent catalytic activity was utilized as a precursor of the metal cofactor. Strong chelation of the dithiophosphate ligands protects the rhodium complex from being deactivated by abundant nucleophiles in cellular environments during conjugation of the cofactor with the protein scaffold. The whole-cell biohybrid catalyst was then activated upon addition of Ag+ ion to dissociate the dithiophosphate ligands and promoted cycloaddition of acetophenone oxime with diphenylacetylene. Furthermore, the activity of the Cp*Rh(III)-linked whole-cell biohybrid catalyst was enhanced 2.1-fold by introducing glutamate residues at positions adjacent to the Cp*Rh(III) cofactor. These results indicate that the use of the Cp*Rh(III)-dithiophosphate complex with switchable activity from a “latent” form to an “active” form provides a new strategy for generating whole-cell biohybrid catalysts.
  • Shunsuke Kato, Akira Onoda, Naomasa Taniguchi, Ulrich Schwaneberg, Takashi Hayashi
    ChemBioChem 22 4 679 - 685 2021年02月15日 [査読有り]
     
    Directed evolution of Cp*RhIII-linked nitrobindin (NB), a biohybrid catalyst, was performed based on an in vitro screening approach. A key aspect of this effort was the establishment of a high-throughput screening (HTS) platform that involves an affinity purification step employing a starch-agarose resin for a maltose binding protein (MBP) tag. The HTS platform enables efficient preparation of the purified MBP-tagged biohybrid catalysts in a 96-well format and eliminates background influence of the host E. coli cells. Three rounds of directed evolution and screening of more than 4000 clones yielded a Cp*RhIII-linked NB(T98H/L100K/K127E) variant with a 4.9-fold enhanced activity for the cycloaddition of acetophenone oximes with alkynes. It is confirmed that this HTS platform for directed evolution provides an efficient strategy for generating highly active biohybrid catalysts incorporating a synthetic metal cofactor.
  • Shunsuke Kato, Akira Onoda, Alexander R. Grimm, Kengo Tachikawa, Ulrich Schwaneberg, Takashi Hayashi
    Inorganic Chemistry 59 19 14457 - 14463 2020年10月05日 [査読有り]
     
    A Cp*Rh(III)-dithiophosphate cofactor with "latent"catalytic activity was developed to construct an artificial metalloenzyme representing a new type of biohybrid catalyst which is capable of promoting C(sp2)-H bond functionalization within the β-barrel structure of nitrobindin (NB). To covalently conjugate the Cp*Rh(III) cofactor into a specific position of the hydrophobic cavity of NB via a maleimide-Cys linkage, strong chelation of the dithiophosphate ligand is employed to protect the rhodium metal center against attack by nucleophilic amino acid residues in the protein. It is found that subsequent addition of the Ag+ ion induces dissociation of the dithiophosphate ligands, thereby activating the catalytic activity of the Cp*Rh(III) cofactor. The resulting "active"biohybrid catalyst promotes cycloaddition of acetophenone oxime with diphenylacetylene via C(sp2)-H bond activation. This catalytic activity is enhanced 2.3-fold with the introduction of two glutamate residues (A100E/L125E) adjacent to the Cp*Rh(III) cofactor. The Cp*Rh(III) cofactor with switchable activity from a "latent"form to an "active"form provides a new strategy for generating biohybrid catalysts incorporating a variety of highly reactive transition metal complexes specifically within its protein scaffolds.
  • Taku Miyazawa, Takuro Suzuki, Yuhei Kumagai, Koji Takizawa, Takashi Kikuchi, Shunsuke Kato, Akira Onoda, Takashi Hayashi, Yuji Kamei, Futa Kamiyama, Masahiro Anada, Masahiro Kojima, Tatsuhiko Yoshino, Shigeki Matsunaga
    Nature Catalysis 3 10 851 - 858 2020年10月01日 [査読有り]
     
    The development of robust and reactive chiral catalysts is a fundamental aim in asymmetric catalysis, and crucial for providing efficient methods for synthesizing chiral molecules. Chiral paddle-wheel bimetallic complexes provide a highly tunable chiral environment in rhodium-catalysed asymmetric carbene/nitrene transfer reactions and Lewis acid-catalysed reactions. Chiral paddle-wheel complexes having other transition metals as the reactive metal centre, however, have not yet been identified in asymmetric catalysis. Here, we report the synthesis, structures and high catalytic performances of chiral paddle-wheel diruthenium complexes. The cationic chiral diruthenium complex [Ru2((S)-BPTPI)4]+ exhibited remarkable reactivity as a Lewis acid catalyst for asymmetric hetero-Diels–Alder reactions, achieving a turnover number of up to 1,880,000 with high enantioselectivity (>90% e.e.). The chiral diruthenium complexes also exhibited good reactivity and high enantioselectivity in C–H amination and cyclopropanation reactions under oxidizing conditions, indicating their high tolerance towards oxidation. Our results reveal the chiral paddle-wheel diruthenium scaffold as a promising platform for asymmetric catalysis. [Figure not available: see fulltext.].
  • Akira Onoda, Nozomu Inoue, Eigo Sumiyoshi, Takashi Hayashi
    ChemBioChem 21 9 1274 - 1278 2020年05月04日 [査読有り][通常論文]
     
    Site-specific modification of peptides and proteins is a key aspect of protein engineering. We developed a method for modification of the N terminus of proteins using 1H-1,2,3-triazole-4-carbaldehyde (TA4C) derivatives, which can be prepared in one step. The N-terminal specific labeling of bioactive peptides and proteins with the TA4C derivatives proceeds under mild reaction conditions in excellent conversion (angiotensin I: 92 %, ribonuclease A: 90 %). This method enables site-specific conjugation of various functional molecules such as fluorophores, biotin, and polyethylene glycol attached to the triazole ring to the N terminus. Furthermore, a functional molecule modified with a primary amine moiety can be directly converted into a TA4C derivative through a Dimroth rearrangement reaction with 1-(4-nitrophenyl)-1H-1,2,3-triazole-4-carbaldehyde. This method can be used to obtain N-terminal-modified proteins via only two steps: 1) convenient preparation of a TA4C derivative with a functional group and 2) modification of the N terminus of the protein with the TA4C derivative.
  • Nozomu Inoue, Akira Onoda, Takashi Hayashi
    Bioconjugate Chemistry 30 9 2427 - 2434 2019年09月18日 [査読有り][通常論文]
     
    Site-specific modification of peptides and proteins is an important method for introducing an artificial function to the protein surface. Recently, we found that new bioconjugation reagents, 6-(azidomethyl)-2-pyridinecarbaldehyde (6AMPC) derivatives, allow specific N-terminal modification and enhance the reaction rate of the subsequent bioconjugation in a chelation-assisted CuAAC reaction. The N-terminal specific azide-labeling of bioactive peptides and proteins occurs under mild reaction conditions with 6AMPC derivatives (angiotensin I: 90%, ribonuclease A: 90%). Kinetic analysis of the CuAAC reaction with azide-labeled proteins reveals that the ligation is promoted in the presence of a copper-chelating pyridine moiety. Importantly, the introduction of an electron-donating methoxy group to the pyridine moiety further accelerates the CuAAC ligation. We demonstrate that this method enables site-specific conjugation of various functional molecules such as fluorophores, biotin, and polyethylene glycol.
  • Koji Oohora, Akira Onoda, Takashi Hayashi
    Accounts of Chemical Research 52 4 945 - 954 2019年04月 [査読有り][通常論文]
     
    ConspectusIn nature, heme cofactor-containing proteins participate not only in electron transfer and O 2 storage and transport but also in biosynthesis and degradation. The simplest and representative cofactor, heme b, is bound within the heme pocket via noncovalent interaction in many hemoproteins, suggesting that the cofactor is removable from the protein, leaving a unique cavity. Since the cavity functions as a coordination sphere for heme, it is of particular interest to investigate replacement of native heme with an artificial metal complex, because the substituted metal complex will be stabilized in the heme pocket while providing alternative chemical properties. Thus, cofactor substitution has great potential for engineering of hemoproteins with alternative functions. For these studies, myoglobin has been a focus of our investigations, because it is a well-known oxygen storage hemoprotein. However, the heme pocket of myoglobin has been only arranged for stabilizing the heme-bound dioxygen, so the structure is not suitable for activation of small molecules such as H 2 O 2 and O 2 as well as for binding an external substrate. Thus, the conversion of myoglobin to an enzyme-like biocatalyst has presented significant challenges. The results of our investigations have provided useful information for chemists and biologists. Our own efforts to develop functionalized myoglobin have focused on the incorporation of a chemically modified cofactor into apomyoglobin in order to (1) construct an artificial substrate-binding site near the heme pocket, (2) increase cofactor reactivity, or (3) promote a new reaction that has never before been catalyzed by a native heme enzyme. In pursuing these objectives, we first found that myoglobin reconstituted with heme having a chemically modified heme-propionate side chain at the exit of the heme pocket has peroxidase activity with respect to oxidation of phenol derivatives. Our recent investigations have succeeded in enhancing oxidation and oxygenation activities of myoglobin as well as promoting new reactions by reconstitution of myoglobin with new porphyrinoid metal complexes. Incorporation of suitable metal porphyrinoids into the heme pocket has produced artificial enzymes capable of efficiently generating reactive high valent metal-oxo and metallocarbene intermediates to achieve the catalytic hydroxylation of C(sp 3 )-H bonds and cyclopropanation of olefin molecules, respectively. In other efforts, we have focused on nitrobindin, an NO-binding hemoprotein, because aponitrobindin includes a β-barrel cavity, which provides a robust structure highly similar to that of the native holoprotein. It was expected that the aponitrobindin would be suitable for development as a protein scaffold for a metal complex. Recently, it was confirmed that several organometallic complexes can bind to this scaffold and function as catalysts promoting hydrogen evolution or C-C bond formation. The hydrophobic β-barrel structure plays a significant role in substrate binding as well as controlling the stereoselectivity of the reactions. Furthermore, these catalytic activities and stereoselectivities are remarkably improved by mutation-dependent modifications of the cavity structure for the artificial cofactor. This Account demonstrates how apoproteins of hemoproteins can provide useful protein scaffolds for metal complexes. Further development of these concepts will provide a useful strategy for generation of robust and useful artificial metalloenzymes.
  • Daniel F. Sauer, Takashi Matsuo, Akira Onoda, Jun Okuda, Takashi Hayashi
    Advances in Bioorganometallic Chemistry 307 - 328 2018年12月06日 
    A biohybrid catalyst where a metal complex is embedded in a cavity of a protein can be regarded as an artificial metalloenzyme. In particular, incorporation of synthetic organometallic species in a protein matrix will promote catalytic reactions which cannot be seen in nature. This chapter focuses on olefin metathesis via C=C bond formation/cleavage catalyzed by biohybrid catalysts consisting of Hoveyda-Grubbs (HG) type Ru complex attached to protein. Robust β-barrel proteins, nitrobindin and FhuA, and α-chymotrypsin with a deep cleft are considered as the protein scaffold in this chapter. The HG-type complexes introduced into the scaffolds are found to catalyze ring-opening metathesis polymerization and ring-closing metathesis with good chemoselectivity. This strategy will serve as a new method to construct an attractive biohybrid catalyst for abiological transformations in aqueous media.
  • Tomoki Himiyama, Naomasa Taniguchi, Shunsuke Kato, Akira Onoda, Takashi Hayashi
    Angewandte Chemie International Edition 56 44 13533  Wiley-Blackwell 2017年10月 [査読有り][通常論文]
  • Tomoki Himiyama, Naomasa Taniguchi, Shunsuke Kato, Akira Onoda, Takashi Hayashi
    Angewandte Chemie 129 44 13806  Wiley-Blackwell 2017年10月 [査読有り][通常論文]
  • Koji Oohora, Yoshitaka Onuma, Yuta Tanaka, Akira Onoda, Takashi Hayashi
    Chemical Communications 53 51 6879 - 6882 2017年 [査読有り][通常論文]
     
    Supramolecular assembly of an engineered hemoprotein with an externally-attached heme moiety via an azobenzene or stilbene linker demonstrates drastic structural transitions between two distinct forms: the thermodynamically stable fiber-type assembly and the kinetically trapped metastable micelle-type assembly induced by transient thermal stimulus.
  • Onoda A, Harada H, Uematsu T, Kuwabata S, Yamanaka R, Sakurai S, Hayashi T
    RSC Advances 7 2 1089 - 1092 2017年 [査読有り][通常論文]
     
    A WO3 photoelectrode immobilizing a fibrous gold nanoparticle (AuNP) assembly using an amyloid-β (Aβ) peptide was constructed and its ability for photocurrent generation upon visible light irradiation was investigated. AuNPs attached using Aβ peptide (Aβ-AuNP) assemble with a fibrous structure at pH 4.5, which disperses at pH 11. The modified Aβ-AuNPs are immobilized on the surface of WO3 fabricated on a fluorine-doped tin oxide (FTO) electrode (Aβ-AuNPass@WO3/FTO or Aβ-AuNPdis@WO3/FTO, respectively). The photocurrent generation response of the Aβ-AuNPass@WO3/FTO electrode is clearly increased relative to that of Aβ-AuNPdis@WO3/FTO upon visible light irradiation (λ = 420-750 nm), indicating that the fibrous AuNP assembly enhances the visible light response of the WO3 photoelectrode.
  • Koji Oohora, Yoshitaka Onuma, Yuta Tanaka, Akira Onoda, Takashi Hayashi
    Chemical Communications 53 51 6879 - 6882 2017年 [査読有り][通常論文]
     
    Supramolecular assembly of an engineered hemoprotein with an externally-attached heme moiety via an azobenzene or stilbene linker demonstrates drastic structural transitions between two distinct forms: the thermodynamically stable fiber-type assembly and the kinetically trapped metastable micelle-type assembly induced by transient thermal stimulus.
  • Onoda A, Taniguchi T, Inoue N, Kamii A, Hayashi T
    European Journal of Inorganic Chemistry 2016 21 3454 - 3459 2016年07月 [査読有り][通常論文]
     
    Gold nanoparticles immobilized on a gold electrode surface were modified with a heme moiety through gold–sulfur bonds and then treated with apocytochrome b562(apoCYT) to yield a reconstituted protein on the gold nanoparticles. Immobilization of apoCYT on the surface of the AuNP-modified electrode was confirmed by the charge-transfer resistance value RCTdetermined using alternating-current electrochemical impedance spectroscopy. The N 1s and Fe 2p peaks in the X-ray photoelectron spectrum support the reconstitution of the heme moiety on the surface of the AuNP electrode. The hemoprotein-immobilized electrode exhibits a ten-fold enhanced electrochemical response relative to the protein immobilized directly on the gold electrode.
  • Hirofumi Harada, Akira Onoda, Taro Uematsu, Susumu Kuwabata, Takashi Hayashi
    Langmuir 32 25 6459 - 6467 2016年06月28日 [査読有り][通常論文]
     
    A method using biomolecules to precisely fabricate the morphology of metal nanoparticles immobilized on the surface of a semiconductor using biomolecules is described. A biotin moiety (Biot) is introduced onto the surface of a gold nanoparticle (AuNP) by covalent coupling with α-lipoic acid to assemble AuNPs in the presence of streptavidin (STV). The assembly of Biot-AuNP/STV is immobilized on the surface of TiO2 chemically modified with 1-(3-aminopropyl)silatrane (APS) to provide a positively charged surface. The Au content immobilized on the surface of TiO2 is clearly increased to 9.5 wt % (Au) as a result of the STV-biotin interaction and the electrostatic interaction between negatively charged Biot-AuNPs and the positively charged surface of APS/TiO2. Transmission electron microscopy (TEM) analysis reveals that the composite has an ordered surface geometry in which Biot-AuNPs are spread over the composite surface in two dimensions. The photocatalytic activity toward decomposition of methyl orange dye promoted by this composite is 55%, which is higher than that of the other composites. The Biot-AuNP/STV@APS/TiO2 composite efficiently reduces O2 molecules at Eonset = 0.23 V vs Ag|AgCl, which is more positive than that of other composites (Eonset = 0.40 to 0.32 V). The result suggests that an increased number of AuNPs immobilized in close contact with the TiO2 surface facilitates photoinduced charge transfer. This strategy, which takes advantage of the specific interactions provided by biomolecules and the chemical modification on the surface, has remarkable potential for efficient fabrication of metal nanoparticles on the surface of the semiconductor, which accelerates the reduction of oxygen molecules.
  • Hassan Osseili, Daniel F. Sauer, Klaus Beckerle, Marcus Arlt, Tomoki Himiyama, Tino Polen, Akira Onoda, Ulrich Schwaneberg, Takashi Hayashi, Jun Okuda
    Beilstein Journal of Organic Chemistry 12 1314 - 1321 2016年06月24日 [査読有り][通常論文]
     
    Copper(I) and copper(II) complexes were covalently linked to an engineered variant of the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA ΔCVFtev ). Copper(I) was incorporated using an N-heterocyclic carbene (NHC) ligand equipped with a maleimide group on the side arm at the imidazole nitrogen. Copper(II) was attached by coordination to a terpyridyl ligand. The spacer length was varied in the back of the ligand framework. These biohybrid catalysts were shown to be active in the Diels-Alder reaction of a chalcone derivative with cyclopentadiene to preferentially give the endo product.
  • Tomoki Himiyama, Daniel F. Sauer, Akira Onoda, Thomas P. Spaniol, Jun Okuda, Takashi Hayashi
    Journal of Inorganic Biochemistry 158 55 - 61 2016年05月01日 [査読有り][通常論文]
     
    A hybrid biocatalyst containing a metal terpyridine (tpy) complex within a rigid β-barrel protein nitrobindin (NB) is constructed. A tpy ligand with a maleimide group, N-[2-([2,2′:6′,2′′-terpyridin]-4′-yloxy)ethyl]maleimide (1), was covalently linked to Cys96 inside the cavity of NB to prepare a conjugate NB-1. Binding of Cu2 +, Zn2 +, or Co2 + ion to the tpy ligand in NB-1 was confirmed by UV-vis spectroscopy and ESI-TOF MS measurements. Cu2 +-bound NB-1 is found to catalyze a Diels-Alder reaction between azachalcone and cyclopentadiene in 22% yield, which is higher than that of the Cu2 +-tpy complex without the NB matrix. The results suggest that the hydrophobic cavity close to the copper active site within the NB scaffold supports the binding of the two substrates, dienophile and diene, to promote the reaction.
  • Toshikazu Ono, Yasushi Hisaoka, Akira Onoda, Koji Oohora, Takashi Hayashi
    Chemistry - An Asian Journal 11 7 1036 - 1042 2016年04月 [査読有り][通常論文]
     
    A supramolecular conjugate of myoglobin (Mb) and water-soluble poly(acrylate), (PA5k and PA25k, where 5k and 25k represent the molecular weight of the polymers, respectively), is constructed on the basis of a noncovalent heme-heme pocket interaction. The modified heme with an amino group linked to the terminus of one of the heme-propionates is coupled to the side-chain carboxyl groups of poly(acrylate) activated by N-hydroxysuccinimide. The ratios of the heme-modified monomer unit and the unmodified monomer unit (m:n) in the polymer chains of Heme-PA5k and Heme-PA25k were determined to be 4.5:95.5 and 3.1:96.9, respectively. Subsequent addition of apoMb to the conjugated polymers provides Mb-connected fibrous nanostructures confirmed by atomic force microscopy. A mixture of the heme-modified polymer and dimeric apomyoglobin as a cross-linker forms a microgel in which the reconstituted myoglobin retains its native exogenous ligand binding activity.
  • Akira Onoda, Nozomu Inoue, Stéphane Campidelli, Takashi Hayashi
    RSC Advances 6 70 65936 - 65940 2016年 [査読有り][通常論文]
     
    Redox-active cytochrome b562 with a tethered azide group on the heme propionate side chain is covalently linked to an acetylene moiety introduced on the sidewall of a single-walled carbon nanotube (SWNT) by copper-catalyzed click chemistry forming a triazole ring with the heme active site directly linked to the SWNT. The cytochrome b562-SWNT hybrid is characterized by electrochemistry and atomic force microscopy.
  • Sauer D.F, Himiyama T, Tachikawa K, Fukumoto K, Onoda A, Mizohata E, Inoue T, Bocola M, Schwaneberg U, Hayashi T, Okuda J
    ACS Catalysis 5 12 7519 - 7522 2015年11月16日 [査読有り][通常論文]
     
    A series of Grubbs-Hoveyda type catalyst precursors for olefin metathesis containing a maleimide moiety in the backbone of the NHC ligand was covalently incorporated in the cavity of the β-barrel protein nitrobindin. By using two protein mutants with different cavity sizes and choosing the suitable spacer length, an artificial metalloenzyme for olefin metathesis reactions in water in the absence of any organic cosolvents was obtained. High efficiencies reaching TON > 9000 in the ROMP of a water-soluble 7-oxanorbornene derivative and TON > 100 in ring-closing metathesis (RCM) of 4,4-bis(hydroxymethyl)-1,6-heptadiene in water under relatively mild conditions (pH 6, T = 25-40 °C) were observed.
  • Hayashi Takashi, Onoda Akira, Oohora Koji
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 250 2015年08月16日 [査読有り][通常論文]
  • Koji Oohora, Ayumu Ogawa, Tamaki Fukuda, Akira Onoda, Jun Y. Hasegawa, Takashi Hayashi
    Angewandte Chemie - International Edition 54 21 6227 - 6230 2015年05月18日 [査読有り][通常論文]
     
    meso-Monobenzoporphycene (mMBPc) and meso-dibenzoporphycene (mDBPc), in which one or two benzene moieties are fused at ethylene-bridged positions (meso-positions) of porphycene, were prepared in an effort to further delocalize the π-electrons within the porphycene molecule. mMBPc and mDBPc were fully characterized by mass spectrometry, 1H and 13CNMR spectroscopy, and X-ray crystallography. The longest-wavelength Q-bands of mMBPc and mDBPc are red-shifted by 92nm and 418, respectively, compared to that of the unsubstituted porphycene (Pc). Electrochemical measurements indicate that the HOMO is destabilized and the LUMO is stabilized by the fused benzene moieties at the meso positions. Furthermore, both XPS and theoretical studies support the presence of a cis tautomeric form in the ground state of mDBPc, despite the fact that essentially all known porphycene derivatives adopt the trans tautomeric form. Put a ring on it: The insertion of two benzene moieties at the meso positions of a porphycene framework yields meso-dibenzoporphycene (mDBPc). The compound has a small electrochemical HOMO-LUMO gap (0.81eV) and an NIR absorption band at 1047nm. X-ray photoelectron spectroscopy and a theoretical study indicate that, unusually for a porphycene derivative, the cis tautomeric form of the porphycene framework is more stable than the trans form.
  • Akira Onoda, Takashi Hayashi
    Current Opinion in Chemical Biology 25 133 - 140 2015年04月 [査読有り][通常論文]
     
    Hydrogenase catalyses reversible transformation of H2 to H+ using an active site which includes an iron or nickel atom. Synthetic model complexes and molecular catalysts inspired by nature have unveiled the structural and functional basis of the active site with remarkable accuracy and this has led to the discovery of active synthetic catalysts. To further improve the activity of such molecular catalysts, both the first and outer coordination spheres should be well-organized and harmonized for an efficient shuttling of H+, electrons, and H2. This article reviews recent advances in the design and catalytic properties of artificial enzymes that mimic the hydrogenase active site and the outer coordination sphere in combination with a peptide or protein scaffold.
  • Akira Onoda, Takashi Hayashi, Michèle Salmain
    Bioorganometallic Chemistry: Applications in Drug Discovery, Biocatalysis, and Imaging 9783527335275 305 - 338 2015年04月 [査読有り][通常論文]
     
    Enzymes are the catalysts of the living world. Nature has tailored proteins to catalyze an incredibly wide range of reactions with exquisite selectivity and efficiency under very mild conditions of temperature, pH, pressure, and so on. Protein engineering combined with molecular modeling techniques affords tailor-made biocatalysts for the industrial production of chiral synthons. Nonetheless, endowing a given protein scaffold with a totally new activity remains a challenging task for the biochemist. Among the current strategies to impart proteins with unnatural activity, those dealing with the construction of artificial metalloenzymes are particularly promising. By definition, artificial metalloenzymes are hybrid catalysts resulting from the incorporation of a transition metal species within a biomacromolecular scaffold. The rationale behind this concept is to combine the wide catalytic scope of transition metal complexes with the high activity and selectivity of biocatalysts. In most of the hybrid catalysts reported so far, the roles devoted to both partners are clearly separated: the metal complex being responsible for reactivity, while the protein environment is used to induce selectivity in the chemical process. In that, artificial metalloenzymes truly resemble enzymes whose efficiency relies on both the active site and the second sphere of coordination (also called the outer coordination sphere). In this chapter, we intend to give an overview of the various anchoring strategies reported over the last decade for the controlled, site-selective attachment of nonnative metal cofactors within protein matrices together with the activity/selectivity displayed by these hybrid enzymes.
  • Akira Onoda, Yuta Tanaka, Toshikazu Ono, Shotaro Takeuchi, Akira Sakai, Takashi Hayashi
    Journal of Porphyrins and Phthalocyanines 19 1-3 510 - 516 2015年01月01日 [査読有り][通常論文]
     
    A non-precious metal catalyst (NPMC) promoting a four-electron oxygen reduction reaction (ORR) was synthesized by heat treatment of myoglobin (Mb) containing a heme (iron protoporphyrin IX) as a source of iron, nitrogen, and carbon atoms. Samples of the mixture of Mb and carbon black (Vulcan XC72R: VC) were pyrolyzed at 740, 840, 940, 1040 or 1140°C under N2 flow. The microstructures of the carbonized Mb catalysts were characterized by XRD, Raman spectroscopy, XPS, and TEM. Results indicate that the iron-containing active site is embedded within the surface structure in an amorphous domain of the carbon materials. The catalyst ink in a 0.05 wt% Nafion solution in isopropanol was coated onto a glassy carbon electrode and the ORR activity of Mb-based NPMCs was evaluated in a rotating disk electrode experiment in an O2-saturated 0.1 M HClO4 solution at 25°C. The catalyst synthesized at 940°C has the highest ORR activity in terms of the onset potential and the current density. In contrast, pyrolytic temperatures above 940°C decrease the activity, suggesting that the active structure of the catalyst apparently decomposes at higher temperatures. The Koutecky-Levich plots indicate that the Mb-based catalyst prepared at 940°C catalyzes four-electron ORR (n = ca. 4). The catalysts prepared at other temperatures have n values of 3.6 at 740°C, 3.7 at 840°C, and 2.9 at 1040°C. The ORR of Mb/VC is diffusion-controlled at potentials lower than 0.3 V (vs. RHE) and the onset potential is 0.84 ± 0.01 V.
  • Takashi Hayashi, Yohei Sano, Akira Onoda
    Israel Journal of Chemistry 55 1 76 - 84 2015年01月 [査読有り][通常論文]
     
    Heme can be removed from a number of native hemoproteins, thus forming corresponding apoproteins, each of which provides a site for binding of a metal complex. In one example, myoglobin, an O2 storage protein, can be reconstituted with iron porphycene to dramatically enhance the O2 affinity. Although it is known that myoglobin has poor enzymatic activity, the insertion of iron corrole or iron porphycene into apomyoglobin increases its H2O2-dependent peroxidase/peroxygenase activities. Furthermore, reconstitution with manganese porphycene promotes hydroxylation of an inert CH bond. It is also of interest to insert a non-porphyrinoid complex into an apoprotein. A cavity of apocytochrome c has been found to bind a diiron carbonyl complex, serving as a functional model of diiron hydrogenase. Aponitrobindin has a rigid β-barrel structure that provides an excellent cavity for covalently anchoring a metal complex. A rhodium complex embedded in the cavity of genetically modified nitrobindin has been found to promote stereoselective polymerization of phenylacetylene.
  • Konrad Herzog, Paula Bracco, Akira Onoda, Takashi Hayashi, Kurt Hoffmann, Anett Schallmey
    Acta Crystallographica Section D: Biological Crystallography 70 11 2875 - 2889 2014年11月01日 [査読有り][通常論文]
     
    CYP154C5 from Nocardia farcinica is a bacterial cytochrome P450 monooxygenase active on steroid molecules. The enzyme has recently been shown to exhibit exclusive regioselectivity and stereoselectivity in the conversion of various pregnans and androstans, yielding 16α-hydroxylated steroid products. This makes the enzyme an attractive candidate for industrial application in steroid hormone synthesis. Here, crystal structures of CYP154C5 in complex with four different steroid molecules were solved at resolutions of up to 1.9 Å. These are the first reported P450 structures from the CYP154 family in complex with a substrate. The active site of CYP154C5 forms a flattened hydrophobic channel with two opposing polar regions, perfectly resembling the size and polarity distribution of the steroids and thus resulting in highly specific steroid binding with Kd values in the range 10-100 nM. Key enzyme-substrate interactions were identified that accounted for the exclusive regioselectivity and stereoselectivity of the enzyme. Additionally, comparison of the four CYP154C5-steroid structures revealed distinct structural differences, explaining the observed variations in kinetic data obtained for this P450 with the steroids pregnenolone, dehydroepiandrosterone, progesterone, androstenedione, testosterone and nandrolone. This will facilitate the generation of variants with improved activity or altered selectivity in the future by means of protein engineering.
  • Akira Onoda, Yoshihiko Kihara, Kazuki Fukumoto, Yohei Sano, Takashi Hayashi
    ACS Catalysis 4 8 2645 - 2648 2014年08月 [査読有り][通常論文]
     
    The hydrogen-evolving diiron complex, (μ-S)2Fe 2(CO)6 with a tethered maleimide moiety was synthesized and covalently embedded within the cavity of a rigid β-barrel protein matrix by coupling a maleimide moiety to a cysteine residue within the β-barrel. The (μ-S)2Fe2(CO)6 core within the cavity was characterized by UV-vis absorption and a characteristic CO vibration determined by IR measurements. The diiron complex embedded within the cavity retains the necessary catalytic activity (TON up to 130 for 6 h) to evolve H2 via a photocatalytic cycle with a Ru photosensitizer in a solution of 100 mM ascorbate and 50 mM Tris/HCl at pH 4.0 and 25 °C. © 2014 American Chemical Society.
  • Kazuki Fukumoto, Akira Onoda, Eiichi Mizohata, Marco Bocola, Tsuyoshi Inoue, Ulrich Schwaneberg, Takashi Hayashi
    ChemCatChem 6 5 1229 - 1235 2014年05月 [査読有り][通常論文]
     
    The incorporation of a Rh complex with a maleimide moiety into the cavity of the nitrobindin β-barrel scaffold by a covalent linkage at the 96-position (Cys) provides a hybrid biocatalyst that promotes the polymerization of phenylacetylene. The appropriate structural optimization of the cavity by mutagenesis enhances the stereoselectivity of the polymer with a trans content of 82 % at 25 °C and pH 8.0. The X-ray crystal structure of one of the hybrid biocatalysts at a resolution of 2.0 Å reveals that the Rh complex is located in the β-barrel cavity without any perturbation to the total protein structure. Crystal structure analysis and molecular modeling support the fact that the stereoselectivity is enhanced by the effective control of monomer access to the Rh complex within the limited space of the protein cavity. Hybrid biocatalysis, β in a barrel: The incorporation of a Rh complex into the cavity of the nitrobindin β-barrel scaffold through a covalent linkage provides a hybrid catalyst that promotes the polymerization of phenylacetylene. The appropriate structural optimization of the cavity by mutagenesis enhances the trans content of the polymer. PPA=Polyphenylacetylene. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Masaaki Omichi, Atsushi Asano, Satoshi Tsukuda, Katsuyoshi Takano, Masaki Sugimoto, Akinori Saeki, Daisuke Sakamaki, Akira Onoda, Takashi Hayashi, Shu Seki
    Nature Communications 5 2014年04月 [査読有り][通常論文]
     
    Protein nanowires exhibiting specific biological activities hold promise for interacting with living cells and controlling and predicting biological responses such as apoptosis, endocytosis and cell adhesion. Here we report the result of the interaction of a single high-energy charged particle with protein molecules, giving size-controlled protein nanowires with an ultra-high aspect ratio of over 1,000. Degradation of the human serum albumin nanowires was examined using trypsin. The biotinylated human serum albumin nanowires bound avidin, demonstrating the high affinity of the nanowires. Human serum albumin-avidin hybrid nanowires were also fabricated from a solid state mixture and exhibited good mechanical strength in phosphate-buffered saline. The biotinylated human serum albumin nanowires can be transformed into nanowires exhibiting a biological function such as avidin-biotinyl interactions and peroxidase activity. The present technique is a versatile platform for functionalizing the surface of any protein molecule with an extremely large surface area. © 2014 Macmillan Publishers Limited. All rights reserved.
  • Yasunori Okamoto, Akira Onoda, Hiroshi Sugimoto, Yu Takano, Shun Hirota, Donald M. Kurtz, Yoshitsugu Shiro, Takashi Hayashi
    Chemical Communications 50 26 3421 - 3423 2014年03月04日 [査読有り][通常論文]
     
    The O2-binding carboxylate-bridged diiron site in DcrH-Hr was engineered in an effort to perform the H2O2-dependent oxidation of external substrates. A His residue was introduced near the diiron site in place of a conserved residue, Ile119. The I119H variant promotes the oxidation of guaiacol and 1,4-cyclohexadiene upon addition of H2O2. © 2014 Royal Society of Chemistry.
  • Tomoki Himiyama, Akira Onoda, Takashi Hayashi
    Chemistry Letters 43 7 1152 - 1154 2014年 [査読有り][通常論文]
     
    A myoglobin-cadmium telluride quantum dot (QD) conjugate was constructed via supramolecular hostguest interactions between a cyclodextrin molecule attached on QD and an adamantyl group covalently linked to the heme. Irradiation of the supramolecular myoglobin-cadmium telluride conjugate generated a photoreduced ferrous myoglobin species via an electron transfer from the photoexcited quantum dot, leading to the formation of CO-bound myoglobin under a CO atmosphere. © 2014 The Chemical Society of Japan.
  • Akira Onoda, Yasuaki Kakikura, Takashi Hayashi
    Dalton Transactions 42 45 16102 - 16107 2013年12月07日 [査読有り][通常論文]
     
    Hierarchical assemblies of the noteworthy photoactive cytochrome b 562 reconstituted with zinc protoporphyrin IX covalently linked with the protein surface were constructed on a gold electrode modified with an apoprotein of cytochrome b562. The integrated photoactive hemoproteins were characterized by electrochemical impedance and quartz crystal microbalance analyses. The protein-immobilized electrode exhibits enhanced photocurrent generation relative to the one having a Zn-substituted hemoprotein monolayer. © 2013 The Royal Society of Chemistry.
  • Yasunori Okamoto, Akira Onoda, Hiroshi Sugimoto, Yu Takano, Shun Hirota, Donald M. Kurtz, Yoshitsugu Shiro, Takashi Hayashi
    Inorganic Chemistry 52 22 13014 - 13020 2013年11月18日 [査読有り][通常論文]
     
    A nonheme diiron active site in a 13 kDa hemerythrin-like domain of the bacterial chemotaxis protein DcrH-Hr contains an oxo bridge, two bridging carboxylate groups from Glu and Asp residues, and five terminally ligated His residues. We created a unique diiron coordination sphere containing five His and three Glu/Asp residues by replacing an Ile residue with Glu in DcrH-Hr. Direct coordination of the carboxylate group of E119 to Fe2 of the diiron site in the I119E variant was confirmed by X-ray crystallography. The substituted Glu is adjacent to an exogenous ligand-accessible tunnel. UV-vis absorption spectra indicate that the additional coordination of E119 inhibits the binding of the exogenous ligands azide and phenol to the diiron site. The extent of azide binding to the diiron site increases at pH ≤ 6, which is ascribed to protonation of the carboxylate ligand of E119. The diferrous state (deoxy form) of the engineered diiron site with the extra Glu residue is found to react more slowly than wild type with O2 to yield the diferric state (met form). The additional coordination of E119 to the diiron site also slows the rate of reduction from the met form. All these processes were found to be pH-dependent, which can be attributed to protonation state and coordination status of the E119 carboxylate. These results demonstrate that modifications of the endogenous coordination sphere can produce significant changes in the ligand binding and redox properties in a prototypical nonheme diiron-carboxylate protein active site. © 2013 American Chemical Society.
  • Yasuaki Kakikura, Akira Onoda, Emi Kubo, Hiroaki Kitagishi, Taro Uematsu, Susumu Kuwabata, Takashi Hayashi
    Journal of Inorganic and Organometallic Polymers and Materials 23 1 172 - 179 2013年01月 [査読有り][通常論文]
     
    Linear assemblies of cytochrome b562 (cyt b562) containing a chemically-modified heme molecule on the protein surface were constructed by successive intermolecular heme-heme pocket interactions and then immobilized onto a gold electrode via a heme molecule anchored on the electrode. The accumulation of the cyt b562 units were confirmed by electrochemical analyses. The average number of proteins in each assembly was estimated to be about 6 units by quartz crystal microbalance and atomic force microscopy (AFM) analyses. The linear assemblies of the cyt b562 units were clearly visualized by AFM as a rod-like architecture with a vertical orientation to the electrode surface. © 2012 Springer Science+Business Media, LLC.
  • Akira Onoda, Takashi Hayashi
    Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry 71 5 452 - 460 2013年 [査読有り][通常論文]
     
    Efforts to develop an attractive biocatalyst with new chemical reactivity and selectivity indicate that promising strategies involve the construction of artificial metalloenzymes generated by incorporation of a metal-containing moiety into a protein scaffold. In this article, we present three recent results focusing on the modification of proteins with artificial metal complexes. First, an artificial hydrogenase model containing a synthetic diiron carbonyl cluster, (μ-S2)[FeI(CO)3]2, held by a native cysteine-containing motif in the cytochrome c protein is described. The diiron carbonyl core anchored by coordination within the protein matrix works well as a catalyst for H2 evolution. Second, a hybrid catalyst containing a rhodium complex with a maleimide moiety at the peripheral position of the cyclopendiene ligand is described. The rhodium complex was inserted into a β-barrel protein scaffold of a mutant of aponitrobindin via a covalent linkage. The hybrid protein acts as a polymerization catalyst and preferentially yields trans-poly(phenylacetylene) (PPA). Finally, an artificial hemoprotein containing an iron porphycene, a structural isomer of hemin, within a heme pocket, is reported. The reconstituted horseradish peroxidase catalyzes the H2O2-dependent oxidation of thioanisole, of which the initial rate is 12-fold faster than that observed for native myoglobin.
  • Koji Oohora, Akira Onoda, Takashi Hayashi
    Chemical Communications 48 96 11714 - 11726 2012年11月07日 [査読有り][通常論文]
     
    A native protein in a biological system spontaneously produces large and elegant assembliesviaself-assembly or assembly with various biomolecules which provide non-covalent interactions. In this context, the protein plays a key role in construction of a unique supramolecular structure operating as a functional system. Our group has recently highlighted the structure and function of hemoproteins reconstituted with artificially created heme analogs. The heme molecule is a replaceable cofactor of several hemoproteins. Here, we focus on the successive supramolecular protein assemblies driven by heme–heme pocket interactions to afford various examples of protein fibers, networks and three-dimensional clusters in which an artificial heme moiety is introduced onto the surface of a hemoproteinviacovalent linkage and the native heme cofactor is removed from the heme pocket. This strategy is found to be useful for constructing hybrid materials with an electrode or with nanoparticles. The new systems described herein are expected to lead to the generation of various biomaterials with functions and characteristic physicochemical properties similar to those of hemoproteins. © 2012 The Royal Society of Chemistry.
  • Onoda A, Fukumoto K, Arlt M, Bocola M, Schwaneberg U, Hayashi T
    Chemical Communications 48 78 9756 - 9758 2012年09月05日 [査読有り][通常論文]
     
    Our group recently prepared a hybrid catalyst containing a rhodium complex, Rh(Cp)(cod), with a maleimide moiety at the peripheral position of the Cp ligand. This compound was then inserted into a β-barrel protein scaffold of a mutant of aponitrobindin (Q96C) via a covalent linkage. The hybrid protein is found to act as a polymerization catalyst and preferentially yields trans-poly(phenylacetylene) (PPA), although the rhodium complex without the protein scaffold normally produces cis PPA. © 2012 The Royal Society of Chemistry.
  • Akira Onoda, Akinori Takahashi, Koji Oohora, Yoshitaka Onuma, Takashi Hayashi
    Chemistry and Biodiversity 9 9 1684 - 1692 2012年09月 [査読有り][通常論文]
     
    Supramolecular hemoprotein assemblies via heme-heme pocket interaction were prepared by synthetic heme dimers containing a linker with charged amino acids and apohemoprotein disulfide dimers. The mixture of the negatively charged heme dimer and the apomyoglobin dimer provides heterotropic fibrous hemoprotein assemblies, which were characterized by size-exclusion chromatography (SEC) and atomic force microscopy (AFM). Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.
  • Akira Onoda, Tomoki Himiyama, Kei Ohkubo, Shunichi Fukuzumi, Takashi Hayashi
    Chemical Communications 48 65 8054 - 8056 2012年07月18日 [査読有り][通常論文]
     
    A myoglobin-cadmium telluride quantum dot conjugate was constructed using an artificial heme modified with a thiol moiety as a linker. Irradiation of the myoglobin-cadmium telluride conjugate generated the photoreduced ferrous myoglobin via an electron transfer from the photoexcited quantum dot, leading to the formation of CO-bound myoglobin under a CO atmosphere. © 2012 Royal Society of Chemistry.
  • Koji Oohora, Sabina Burazerovic, Akira Onoda, Yvonne M. Wilson, Thomas R. Ward, Takashi Hayashi
    Angewandte Chemie - International Edition 51 16 3818 - 3821 2012年04月 [査読有り][通常論文]
     
    Alternating: A cofactor dyad consisting of a heme group (red in picture) and a bis(biotin) unit (blue) was synthesized and shown to specifically bind to both apomyoglobin and streptavidin. In the presence of the dyad, the 1:1 association of a disulfide-bridged myoglobin dimer (green) with streptavidin (gray) afforded a submicrometer-sized fibrous alternating copolymer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Akira Onoda, Yasuaki Kakikura, Taro Uematsu, Susumu Kuwabata, Takashi Hayashi
    Angewandte Chemie - International Edition 51 11 2628 - 2631 2012年03月12日 [査読有り][通常論文]
     
    All connected: A protein-immobilized electrode comprising hierarchical assemblies of photoactive cytochrome b 562 reconstituted with zinc protoporphyrin IX exhibits remarkably enhanced photocurrent generation relative to an electrode bearing a single zinc-substituted hemoprotein layer. The protein oligomers, which bear a covalently linked protoporphyrin group, assemble by a supramolecular heme/heme pocket interaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Yohei Sano, Akira Onoda, Takashi Hayashi
    Journal of Inorganic Biochemistry 108 159 - 162 2012年03月 [査読有り][通常論文]
     
    It is of particular interest to mimic the process of intramolecular electron relay at the active site of [FeFe]-hydrogenase in order to understand the mechanism of the catalytic activity of H 2 evolution. We have recently focused on using the native CXXCH peptide sequence of the C-terminal segment of cytochrome c 556 as a platform which holds a diiron carbonyl cluster via two cysteines and have attached a ruthenium photosensitizer via a histidine. The modified peptide with the two metal moieties is found to act as the photocatalyst for H 2 evolution with a turnover number of ~ 9 over 2 h at pH 8.5 in the presence of ascorbate as a sacrificial reagent. © 2011 Elsevier Inc. All rights reserved.
  • Yohei Sano, Akira Onoda, Takashi Hayashi
    Chemical Communications 47 29 8229 - 8231 2011年08月07日 [査読有り][通常論文]
     
    The diiron carbonyl cluster is held by a native CXXC motif, which includes Cys14 and Cys17, in the cytochrome c sequence. It is found that the diiron carbonyl complex works well as a catalyst for H2 evolution. It has a TON of ∼80 over 2 h at pH 4.7 in the presence of a Ru-photosensitizer and ascorbate as a sacrificial reagent in aqueous media. © 2011 The Royal Society of Chemistry.
  • A. Onoda, Y. Okamoto, H. Sugimoto, Y. Shiro, Hayashi
    Inorg. Chem. 2011年07月 [査読有り][通常論文]
  • Koji Oohora, Akira Onoda, Hiroaki Kitagishi, Hiroyasu Yamaguchi, Akira Harada, Takashi Hayashi
    Chemical Science 2 6 1033 - 1038 2011年06月 [査読有り][通常論文]
     
    Artificial self-assembling systems comprised of proteins have the potential not only for mimicking naturally occurring protein clusters but also for creating functionalized supramolecular polymers. Here we report a new type of a supramolecular protein polymer which utilizes the original character and reactivity of the monomer protein. Myoglobin, an oxygen storage hemoprotein, was chosen as the monomer unit and was provided with an externally-attached heme on the protein surface which drives the formation of the fibrous supramolecular assembly through successive interprotein interactions between the external heme and the protein matrix. This assembly governed by myoglobin characteristics shows chemically-responsive stability and can be converted into extremely large protein clusters via cross-linking. Interestingly, the assembly retains the oxygen storage function. Our present system can be used for construction of smart nanobiomaterials using various hemoproteins. © The Royal Society of Chemistry 2011.
  • Sano Y, Onoda A, Sakurai R, Kitagishi H, Hayashi T
    Journal of Inorganic Biochemistry 105 5 702 - 708 2011年05月 [査読有り][通常論文]
     
    Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the α-domain of MT (MTα) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible, CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTα matrix with Fe II4-MTα and CoII4-MTα species existing in water. Furthermore, the FeII4- MTα species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with FeII4-MTα (1:1) was found to proceed with a conversion of 98% over a period of 6 h at 25 °C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix. © 2011 Elsevier Inc.
  • Akira Onoda, Yuichi Ueya, Taiki Sakamoto, Taro Uematsu, Takashi Hayashi
    Chemical Communications 46 48 9107 - 9109 2010年12月28日 [査読有り][通常論文]
     
    Interaction of apohemoprotein with a covalently immobilized heme moiety onto a gold nanoparticle surface resulted in supramolecular hemoprotein-gold nanoparticle conjugates. The addition of an apohemoprotein dimer further led to a densely-packed hemoprotein-gold nanoparticle assembly, which was visualized by TEM and AFM measurements. © 2010 The Royal Society of Chemistry.
  • Akira Onoda, Hirokazu Nagai, Satoe Koga, Takashi Hayashi
    Bulletin of the Chemical Society of Japan 83 4 375 - 377 2010年 [査読有り][通常論文]
     
    Artificial prosthetic groups tethering a polyamine moiety at the terminal of two peripheral hemepropionate side chains as a molecular interface were inserted into apocytochrome b562 to provide positively charged reconstituted hemoproteins, which exhibit a strong binding with double-stranded DNA. © 2010 The Chemical Society of Japan.
  • Hirokazu Nagai, Akira Onoda, Takashi Matsuo, Takashi Hayashi
    Supramolecular Chemistry 22 1 57 - 64 2010年01月 [査読有り][通常論文]
     
    Two different types of artificial glycosylated haemins (glycohaemins), in which a monosaccharide (galactose) or a disaccharide (lactobionic acid, 4-O-β-galactopyranosyl-D-gluconic acid) was introduced at the terminals of the two haempropionate side chains, were synthesised to serve as a designed interface on the myoglobin surface. These glycohaemins were successfully inserted into apomyoglobin to yield an artificial glycoprotein by the conventional method. The interprotein interaction between the reconstituted myoglobin and peanut agglutinin lectin (PNA), a β-galactose-recognising protein, was confirmed by two different assay systems, i.e. a fluorometric assay using the fluorescein isothiocyanate-labelled lectin and an ELISA-like assay using the peroxidase-labelled lectin. The results revealed that each myoglobin reconstituted with the glycohaemin makes a complex with PNA, in which the glycoprotein with the disaccharides showed a higher binding affinity with the lectin compared to the glycoprotein with the monosaccharides, suggesting that the binding property clearly depends on the deposited carbohydrate surface on the myoglobin. © 2010 Taylor & Francis.
  • Akira Onoda, Takako Suzuki, Hiroaki Ishizuka, Rumiko Sugiyama, Shinya Ariyasu, Takeshi Yamamura
    Journal of Peptide Science 15 12 832 - 841 2009年12月 [査読有り][通常論文]
     
    It is well known that the functions of metalloproteins generally originate from their metal-bindingmotifs. However, the intrinsic nature of individual motifs remains unknown, particularly the details about metal-binding effects on the folding of motifs; the converse is also unknown, although there is no doubt that the motif is the core of the reactivity for each metalloprotein. In this study, we focused our attention on the zinc-binding motif of the metzincin clan family, HEXXHXXGXXH; this family contains the general zinc-binding sequence His-Glu-Xaa-Xaa-His (HEXXH) and the extended GXXH region. We adopted the motif sequence of stromelysin-1 and investigated the folding properties of the Trp-labeled peptides WAHEIAHSLGLFHA (STR-W1), AWHEIAHSLGLFHA (STR-W2), AHEIAHSLGWFHA (STR-W11), and AHEIAHSLGLFHWA (STR-W14) in the presence and absence of zinc ions in hydrophobic micellar environments by circular dichroism (CD) measurements. We accessed successful incorporation of these zinc peptides into micelles using quenching of Trp fluorescence. Results of CD studies indicated that two of the Trp-incorporated peptides, STR-W1 and STR-W14, exhibited helical folding in the hydrophobic region of cetyltrimethylammonium chloride micelle. The NMR structural analysis of the apo STR-W14 revealed that the conformation in the C-terminus GXXH region significantly differred between the apo state in the micelle and the reported Zn-bound state of stromelysin-1 in crystal structures. The structural analyses of the qualitative Zn-binding properties of this motif peptide provide an interesting Zn-binding mechanism: the minimum consensus motif in the metzincin clan, a basic zinc-binding motif with an extended GXXH region, has the potential to serve as a preorganized Zn binding scaffold in a hydrophobic environment. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.
  • S. Ariyasu, A. Onoda, R. Sakamoto, T. Yamamura
    Bioconjucate Chem. 2009年11月 [査読有り][通常論文]
  • Takeshi Yamamura, Shingo Suzuki, Tomotaka Taguchi, Akira Onoda, Toshiaki Kamachi, Ichiro Okura
    Journal of the American Chemical Society 131 33 11719 - 11726 2009年08月26日 [査読有り][通常論文]
     
    The application of low-flux sunlight begins with the synthesis of effective antenna systems. This requires the development of dye integrates with optimized dye orientation for effective energy transfer. We here report a series of peptide-linked porphyrin arrays, denoted by Boc-(PorZn,S) n-OBut (n = 2, 4, and 8), that change their dye orientation to increase fluorescence responsively to additive reagents. The B-band absorption (AB) regions of the arrays show blue shifts (dimer, 407.6 nm; tetramer, 408.2 nm; octamer, 407.8 nm) in organic solvents as compared to that of Boc-PorZn,S-OBut (monomer, 422.6 nm) and the fluorescence yield Φ? of the arrays decreases with increasing n, obeying the relationship Φ? = 0.03/n1.5.; however, the arrays are tuned up in fluorescence emission by the addition of 1,2-diaminoethane (en). The addition of a sufficient amount of en increases the fluorescence of the porphyrins in monomer, dimer, tetramer, and octamer by ∼5, ∼12, ∼12, and >730 times, respectively, when compared with that observed in the absence of en. This also causes asymptotic red shifts in absorption (AB) bands (B-band λmax: 410 to 429-430 nm), as well as changes in circular dichroism (CD) spectra, and makes porphyrins approach new mutual asymmetric orientations. Our results show the potentiality of the tunable dye polymers that are a posteriori optimized in dye orientation and fluorescence emission by additive reagents for the development of effective light-harvesting materials. © 2009 American Chemical Society.
  • Ariyasu S, Onoda A, Sakamoto R, Yamamura T
    Dalton Transactions 19 3742 - 3747 2009年 [査読有り][通常論文]
     
    The stoichiometrically controlled complexation of abiological inorganic clusters with proteins is a challenging task that enables us to combine the functions of inorganic clusters with those of biological systems on the basis of chemical characterisation. In this study, we synthesised a 1:1 conjugate between Au 11(PPh 3) 8Cl 3 (Au11) and CGMTIIα, where Au11 is the smallest cluster, which is situated on the boundary of molecules and nanoparticles, having discrete electronic states and exhibiting Coulomb blockade; on the other hand, CGMTIIα is a twelve-cysteine (Cys)-containing peptide consisting of the α-domain of rat liver metallothionein II (MTIIα) - a heavy metal-binding protein - and an addendum, cysteine-glycine (CG). The Cys residue of the N-terminus is used as a site for elongation by the native chemical ligation (NCL) method. Titration experiments monitored by circular dichroism spectroscopy indicate that CGMTIIα reacts with Au11 in a ratio of 1:1. The product exhibits a negative Cotton effect at 222 nm, indicating the formation of a short a-helix. The composition of this hybrid module is quantified as Au 11(PPh 3) 4(S-Cys) 6 by transmission electron microscopy (core size observation), energy-dispersive X-ray spectroscopy (elemental analysis), Ellman test (uncoordinated Cys residues), and high-performance liquid chromatography (quantification of eliminated PPh 3). These results, as well as those obtained from the simulations of Au 4f X-ray photoelectron spectra, suggest that the Au cluster of this product is Au 11(PPh 3) 4(S-Cys) 6. We also prepared F3F3-CGMTIIα, where F3F3 is a zinc finger peptide with two domains, in order to demonstrate the applicability of the NCL method to the elongation of CGMTIIα. F3F3-CGMTIIα also reacts with Au11 to yield a 1:1 conjugate without interfering in the folding of the zinc finger. © 2009 The Royal Society of Chemistry.
  • Akira Onoda, Masahiro Igarashi, Satoshi Naganawa, Kiyomi Sasaki, Shinya Ariyasu, Takeshi Yamamura
    Bulletin of the Chemical Society of Japan 82 10 1280 - 1286 2009年 [査読有り][通常論文]
     
    Neutral zinc porphyrin containing flexiblealkyllinker, 5-[4-(5- hydroxypentyloxy)phenyl]-10,15,20-tri-p-tolyl- porphyrinatozinc, was attached to the 5' ends of 20- and 30-bp oligodeoxynucleotides (ODN) by solid-phase synthesis. Zinc porphyrin-modified double-stranded DNA (dsDNAs), which included dsDNAs with porphyrinmoieties on one end and on both ends (ZnPor-ds20, ds20-ZnPor, ZnPor-ds20-ZnPor, ZnPor-ds30, ds30-ZnPor, and ZnPor-ds30-ZnPor), were successfully prepared and were analyzed by variable-temperature UV-vis spectroscopy and CD measurements to elucidate the interaction behavior of the porphyrinring. Detailed investigation revealed that the zinc porphyrin-DNA conjugates exhibited intra-duplex porphyrin-ODN interaction inalow-salt condition and inter-duplex porphyrin- porphyrin interaction inahigh-salt condition. © 2009 The Chemical Society of Japan.
  • Kiyomi Sasaki, Akira Onoda, Mina Mizota, Ryota Sakamoto, Takeshi Yamamura
    Nucleic acids symposium series (2004) 52 695 - 696 2008年 [査読有り][通常論文]
     
    The present paper reveals that double crossover-DNAs (DX) serve as scaffolds for the multiple arrangement of a [Ru(bpy)(3)](2+)-bound zinc finger (ZF) protein, Ru-ZF. This series of results would lead to the realization of the two-dimensional arrangement of functional molecules and nanomaterials on DX-tiles.
  • Ueyama N, Takahashi K, Onoda A, Okamura T.-A, Yamamoto H
    Topics in Current Chemistry 271 155 - 193 2006年10月20日 [査読有り][通常論文]
     
    Amide NH prelocating in the vicinity of a carboxylic acid group shifts the pKa of carboxylic acid to a lower value. A carboxylate anion is stabilized by NH ⋯ O hydrogen bond under hydrophobic conditions. In the case of Ca carboxylate complex, the decrease of the pKa value increases a formation constant involving the protonation process of carboxylic acid. In addition, the NH ⋯ O hydrogen bond controls the covalent character of the Ca - O bond for a totally neutral complex that possesses a shortening Ca - O bond distance. Both factors contribute to a strong binding of polycarboxylate on the surface of CaCO3 crystals. The polycarboxylate ligands with a NH ⋯ O hydrogen bond give nanosized vaterite crystals and are located on the surface of the vaterite agglomerate. The deprotonation of some carboxylic acids leads to conformational change in Asp-X-Gly tripeptides, partially amidated Kemp's acid and monoamidated maleate. Conformational switching between stabilized and activated forms for carboxylate affords an unusual crystal growth of calcite even if one of the conformers has a strong NH ⋯ O hydrogen bond. © Springer-Verlag 2006.
  • Takashi Matsuhira, Hitoshi Yamamoto, Akira Onoda, Taka Aki Okamura, Norikazu Ueyama
    Organic and Biomolecular Chemistry 4 7 1338 - 1342 2006年 [査読有り][通常論文]
     
    In this study, we synthesized two novel carboxylic acid and carboxylate compounds, both of which had an amide group linked with an azomethine moiety to introduce photoinduced switching of the intramolecular NH⋯O hydrogen bond. We suggest that the cis-carboxylate compound forms a stronger intramolecular NH⋯O hydrogen bond than the cis-carboxylic acid compound. © The Royal Society of Chemistry 2006.
  • Daisuke Sakaniwa, Takahiro Ohe, Takashi Misumi, Hideaki Monjushiro, Akira Onoda, Takeshi Yamamura
    Chemistry Letters 34 12 1634 - 1635 2005年12月05日 [査読有り][通常論文]
     
    The peptide ligand, Cys-Pro-Leu-Cys, was covalently immobilized on the surface of quartz via (3-aminopropyl) triethoxysilane (APTES) by the general peptide-synthesis method; then, Ni2+ was introduced into this surface to construct the [Ni(S-Cys)4]2- unit contained in the active site of hydrogenases. Copyright © 2005 The Chemical Society of Japan.
  • Akira Onoda, Nozomi Arai, Naoto Shimazu, Hitoshi Yamamoto, Takeshi Yamamura
    Journal of the American Chemical Society 127 47 16535 - 16540 2005年11月30日 [査読有り][通常論文]
     
    Zinc finger fusion proteins, having a Ca-binding site from troponin C, were created to develop Ca-responsive regulation of DNA binding. The typical zinc finger folding of a novel fusion protein with a single finger, F2-Tn, was investigated using UV-vis spectroscopy of the Co-substituted form and CD experiments. Detailed structural analyses of F2-Tn/Zn2+ using NMR experiments and structural calculations clarify that our fusion protein gives a native zinc finger folding with the artificial Ca-binding domain intervening two helices. The Ca-responsive DNA-binding affinity of troponin-fused protein with two fingers (using F1F2-Tn) was investigated by electrophoretic mobility shift assay (EMSA). EMSA analyses of F1F2-Tn were performed under the conditions of various concentrations of the Ca ion. F1F2-Tn has a Kd value of 5.8 nM in the absence of Ca ion and shows a higher Kd value of 13 nM in the presence of 100 equiv of Ca ion. The artificially designed fusion zinc finger protein with a Ca-binding domain has Ca-responsive DNA-binding affinity. It is leading to a better understanding of the construction of zinc finger-based artificial transcriptional factors with a Ca switch. © 2005 American Chemical Society.
  • Onoda A, Haruna H, Yamamoto H, Takahashi K, Kozuki H, Okamura T.-A, Ueyama N
    European Journal of Organic Chemistry 4 641 - 645 2005年02月11日 [査読有り][通常論文]
     
    We report an unprecedented, proton-driven ring transformation from a chair to a twist-boat conformation in the doubly amide-derived Kemp's acid compounds r-1,c-3,c-5-(CH3)3-3,5-(Ph2CHNHCO) 2C6H6-1-COOH (1) and (NMe4){r-1,c-3, c-5-(CH3)3-3,5-(Ph2CHNHCO)2C 6H6-1-COO-} (2) with a protonated and deprotonated carboxyl group, respectively. Each conformation was determined by X-ray analyses and 1H NMR spectroscopy. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
  • Kanamori D, Yamada Y, Onoda A, Okamura T.-A, Adachi S, Yamamoto H, Ueyama N
    Inorganica Chimica Acta 358 2 331 - 338 2005年01月25日 [査読有り][通常論文]
     
    Iron(III) porphinate complexes of phenolate that have NH⋯O hydrogen bonds on the coordinating oxygen were synthesized as models of heme catalase. The NH⋯O hydrogen bonds in the complexes lower an electron donation from the coordinating oxygen to iron and induce a long Fe-O bond and a positive redox potential. Iron(III) porphinate complexes of phenolate that have NH⋯O hydrogen bonds on the coordinating oxygen, [FeIII(OEP){O-2,6-(RCONH) 2C6H3}] (R = CF3 (1), CH3 (3)) and [FeIII(OEP)(O-2-RCONHC6H4)] (R = CF3 (2), CH3 (4)) (OEP = 2,3,7,8,12,13,17,18-octaethyl- 21H, 23H-porphinato), were synthesized and characterized as models of heme catalase. The presence of NH⋯O hydrogen bonds was established by their crystal structures and IR shifts of the amide NH band. The crystal structure of 1 shows an extremely elongated Fe-O bond, 1.926(3) Å, compared to 1.887(2) Å in 2 or 1.848(4) Å in [FeIII(OEP)(OPh)]. The NH⋯O hydrogen bond decreases an electron donation from oxygen to iron, resulting in a long Fe-O bond and a positive redox potential. © 2004 Elsevier B.V. All rights reserved.
  • Onoda A, Yamamoto H, Yamada Y, Lee K, Adachi S, Okamura T.-A, Yoshizawa-Kumagaye K, Nakajima K, Kawakami T, Aimoto S, Ueyama N
    Biopolymers - Peptide Science Section 80 2-3 233 - 248 2005年 [査読有り][通常論文]
     
    Aspartic acid protease model peptides Z-Phe-Asp(COOH)-Thr-Gly-Ser-Ala-NHCy (1) and AdCO-Asp(COOH)-Val-Gly-NHBzl (3), and their aspartate anions (NEt 4)[Z-Phe-Asp-(COO-)-Thr-Gly-Ser-Ala-NHCy] (2) and (NEt4)[AdCO-Asp(COO-)-Val-Gly-NHBzl] (4), having an invariant primary sequence of the Asp-X(Thr,Ser)-Gly fragment, were synthesized and characterized by 1H-NMR, CD, and infrared (IR) spectroscopies. NMR structure analyses indicate that the Asp Oδ atoms of the aspartate peptide 2 are intramolecularly hydrogen-bonded with Gly, Ser, Ala NH, and Ser OH, supporting the rigid β-turn-like conformation in acetonitrile solution. The tripeptide in the aspartic acid 3 forms an inverse γ- turn structure, which is converted to a β-turn-like conformation because of the formation of the intramolecular NH ⋯ O- hydrogen bonds with the Asp Oδ in 4. Such a conformational change is not detected between dipeptides AdCO-Asp(COOH)-Va-NHAd (5) and (NEt4)[AdCO- Asp(COO-)-Val-NHAd] (6). The pKa value of side-chain carboxylic acid (5.0) for 3 exhibits a lower shift (0.3 unit) from that of 5 in aqueous polyethyleneglycol lauryl ether micellar solution. NMR structure analyses for 3 in an aqueous micellar solution indicate that the preorganized turn structure, which readily forms the NH ⋯ O- hydrogen bonds, lowers the pKa value and that resulting hydrogen bonds stabilize the rigid conformation in the aspartate anion state. We found that the formation of the NH ⋯ O- hydrogen bonds involved in the hairpin turn is correlated with the protonation and deprotonation state of the Asp side chain in the conserved amino acid fragments. © 2004 Wiley Periodicals, Inc.
  • Onoda A, Okamura T.-A, Yamamoto H, Ueyama N
    Acta Crystallographica Section E: Structure Reports Online 60 8 M1196 - M1198 2004年08月 [査読有り][通常論文]
     
    The title compound, {[Tb(C11H11N2O 4)3(H2O)3]·H 2O}n, has a Tb ion coordinated by bulky benzoate ligands. The Tb ion coordination sphere is occupied by nine O atoms, five from benzoate groups, three from water molecules and one from an amide carbonyl group of a neighboring ligand. Five amide NH groups of the three ligands are involved in intramolecular N-H⋯O hydrogen bonds. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.
  • Onoda A, Yamada Y, Nakayama Y, Takahashi K, Adachi H, Okamura T.-A, Nakamura A, Yamamoto H, Ueyama N, Vyprachticky D, Okamoto Y
    Inorganic Chemistry 43 14 4447 - 4455 2004年07月12日 [査読有り][通常論文]
     
    Novel benzoic acid ligands with bulky amide groups at the ortho position, 2,6-(MeCONH)2C6H3CO2H (1) and 2,6-(t-BuCONH)2C6H3CO2H (2), and their tris- and tetrakis (carboxylate) complexes with Ca(II) and Tb(III) ions, (NEt4)2-[CaII{O2C-2,6-(t-BuCONH) 2C6H3}4] (4), [Tb{O2C-2,6-(t-BuNHCO) 2C6H3}3(H2O) 3}] (5), and (NMe)4[Tb{O2C-2,6-(t-BuNHCO) 2C6H3}4(thf)] (6), were synthesized. The formation of the NH⋯O hydrogen bonds between the amide NH and carboxylate for 2, (NEt4){2,6-(t-BuCONH)2C 6H3CO2} (3), and 4 was determined by 1H NMR spectroscopy in solution and in the solid state (CRAMPS, IR). The ligand exchange reactions were attempted between 4 and a large excess of 2,4,6- Me3C6H3CO2H in chloroform-d solution; however, exchange reaction did not take place, indicating that the Ca(II) ions bound strongly to the carboxylate in 4. The Ca(II) ion binding properties with the benzoate derivatives were also examined using Tb(III) ion as a fluorescence probe. These results indicate that the NH⋯O hydrogen bonding between the amide NH and the oxygen atom of the carboxylate contributes to strong Ca(II) binding and prevents the dissociation of the calcium-carboxylate bond. The X-ray structural analyses of these complexes revealed that the NH⋯O hydrogen-bonded carboxylate ligands prefer the chelate-type coordination and create a mononuclear {Ca(O2CR) 4}2- or {Tb(O2CR)4}- core with anionic charge, which is known only in the active site of calcium-binding proteins.
  • Akira Onoda, Mototsugu Doi, Kazuyuki Takahashi, Taka Aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Chemistry Letters 33 4 466 - 467 2004年04月 [査読有り][通常論文]
     
    A novel poly(vinyl phosphate) ligand was synthesized as a model of biopolymer ligands containing the OH⋯O hydrogen bonds and CaHPO 4·2H2O (brushite) composites with the polymer ligands were also prepared. Successful detection of the polymer ligand binding to the CaHPO4·2H2O crystals is achieved by 31P MAS NMR with 1 pda (single pulse with decoupling and phase cycling) sequence, which enhances 31P signals of the phosphate polymer having shorter T1 value.
  • Takahashi K, Doi M, Kobayashi A, Taguchi T, Onoda A, Okamura T.-A, Yamamoto H, Ueyama N
    Journal of Crystal Growth 263 1-4 552 - 563 2004年03月01日 [査読有り][通常論文]
     
    Novel poly(allylaminocarboxylate) ligands, which have a carboxylate and the neighboring amide group in the same side-chain, were synthesized as model ligands for crystalline CaCO3 biominerals. Poly{N-allyl-malonamate}, poly{N-allyl-succinamate} and poly{4-allylcarbamoyl-butyrate} form 6-, 7- or 8-membered ring intra-side-chain NH·O hydrogen bonds, respectively, between the carboxylate and the neighboring amide NH in the carboxylate anion state, although the formation of each intra-side-chain NH·O hydrogen bond is independent on the stereoisomers of the polymer main-chain. In the polymer ligand-CaCO3 composites, strong binding of polymer ligands to CaCO3 crystals is caused by stabilizing a Ca-O (carboxylate) bond due to the pKa shift of carboxylic acid by the NH·O hydrogen bond. Furthermore, the strong Ca binding in CaCO3 composites stabilizes the meta-stable morphology of CaCO3 vaterite crystals. © 2004 Elsevier B.V. All rights reserved.
  • Kazuyuki Takahashi, Mototsugu Doi, Atsuko Kobayashi, Takahisa Taguchi, Akira Onoda, Taka Aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Chemistry Letters 33 2 192 - 193 2004年02月05日 [査読有り][通常論文]
     
    Poly {1-[(Z)-3-carboxyl-2-propenylaminomethyl]ethylene} binding on the edge of calcite crystals was observed directly by 13C CP/MAS NMR and FE/SEM measurements. Comparing the results taken both before and after the washing process, we were able to make these observation because the polymer ligand weakly bound to the CaCO3 crystals.
  • Onoda A, Yamada Y, Takeda J, Nakayama Y, Okamura T.-A, Doi M, Yamamoto H, Ueyama N
    Bulletin of the Chemical Society of Japan 77 2 321 - 329 2004年02月 [査読有り][通常論文]
     
    The formation of the NH⋯O hydrogen bonds of carboxylic acids, 2,6-(t-BuCONH)2C6H3COOH (1) and 2-t-BuCONH-6-MeC6H3COOH (2), carboxylate, [NEt 4][2,6-(t-BuCONH)2C6H3COO] (3), and a mixed complex, [N(n-Pr)4][H{2,6-(t-BuCONH)2C 6H3(COO)}2] (4), were determined by X-ray structure analysis, 1H NMR, and IR spectroscopy, both in the solid state and in solution. The amide NH group forms weak intramolecular hydrogen bond between the NH and O=C group, and no NH⋯OH hydrogen bond is formed in the carboxylic acid state. Carboxylate anion 3 forms a strong, intramolecular, partially-covalent hydrogen bond between NH⋯O - (anion). The strength of the NH⋯O hydrogen bonds is also maintained in a solution having a low dielectric constant. The pKa values for 1 and 2, measured in a micellar solution, indicated that one of the important triggers for deprotonation is a direct interaction toward the oxygen atom of the OH group with the amide NHs.
  • Kazuyuki Takahashi, Hitoshi Yamamoto, Akira Onoda, Mototsugu Doi, Takashi Inaba, Masahiko Chiba, Atsuko Kobayashi, Takahisa Taguchi, Taka Aki Okamura, Norikazu Ueyama
    Chemical Communications 4 8 996 - 997 2004年 [査読有り][通常論文]
     
    13C CP/MAS NMR and FE/TEM measurements of the aragonite brick of the nacreous layer of Pinctada fucata indicate that it assembles with highly oriented aragonite nanocrystals, which are regulated by biopolymers. © 2014 The Royal Society of Chemistry.
  • Ueyama N, Takahashi K, Onoda A, Okamura T, Yamamoto H
    Macromolecular Symposia 204 287 - 294 2003年11月 [査読有り][通常論文]
     
    Biologically important Ca-proteins and Ca-biominerals as metal-polymer complexes are often regulated by the complexation and demetalation with the biopolymers. Metal-oxygen bond is supported by NH⋯O hydrogen bonds between coordinating oxyanion and neighboring amide NH and by the successive hydrogen bonding networks. Carboxylate anion under hydrophobic conditions has a high basicity that leads to a covalent Ca-O bond character that is significantly affected by the NH⋯O hydrogen bond. The hydrogen bonds in Asp-containing tripeptide fragments in Ca-proteins presumably control coordination/dissociation of metal-oxygen bonds. Our systematic studies of carboxylate, sulfonate and phosphate Ca(II) complexes demonstrate a relationship between the basicity of oxyanion in carboxylate and hydrogen bonds as cooperating with the oligopeptide conformation in Asp-containing Ca(II) complexes. Hydrogen bonds between carboxylate oxyanion and amide NH, controlled by a conformational switching of oligopeptide fragments, seem to be one of essential factors for the regulatory formation of Ca-proteins and nano-architectures in connection with the interface structure of inorganic and organic phases in biominerals.
  • Akira Onoda, Taka Aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Acta Crystallographica Section E: Structure Reports Online 59 8 O1202 - O1204 2003年08月 [査読有り][通常論文]
     
    In the title compound, C46H36N2O 3, very bulky triphenyl-methyl groups interfere with intermolecular interactions; intramolecular hydrogen bonds N - H·O - H·O=C between the phenol and two amide groups are observed in the structure. © 2003 International Union of Crystallography Printed in Great Britain - all rights reserved.
  • Akira Onoda, Taka-aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Journal of Inorganic Biochemistry 96 1 205 - 205 Elsevier {BV} 2003年07月 [査読有り][通常論文]
  • Onoda A, Kawakita K, Okamura T.-A, Yamamoto H, Ueyama N
    Acta Crystallographica Section E: Structure Reports Online 59 5 M291 - M293 2003年05月 [査読有り][通常論文]
     
    The title complex, chloro(6,6″-dimesityl-2,2′:6′, 2″-terpyridine)palladium(II) tetrachloropalladium(II) dichloromethane tetrasolvate, [PdIICl(dmtpy)]2[PdIICl 4]·4CH2Cl2 (dmtpy is 6,6″-dimesityl-2,2′:6′,2″-terpyridine, C 33H31N3), was synthesized and the crystal structure of the dichloromethane tetrasolvate has been determined. The complex has a distorted square-planar coordination formed by three N atoms and a chloride ion, the distortion caused by the extremely bulky substituted terpyridyl ligand. © 2003 International Union of Crystallography Printed in Great Britain - all rights reserved.
  • Onoda A, Kawakita K, Okamura T.-A, Yamamoto H, Ueyama N
    Acta Crystallographica Section E: Structure Reports Online 59 5 M266 - M267 2003年05月 [査読有り][通常論文]
     
    The title compound, [CuI(dmtpy)(NCMe)](PF6) (dmtpy = 6,6″-dimesityl-2,2′:6′,2″-terpyridine) or [Cu(C 2H3N)(C33H31N3)](PF 6), displays a distorted square-planar coordination, with four N atoms from dmtpy and acetonitrile molecules, as a result of the extremely bulky terpyridyl ligand. © 2003 International Union of Crystallography Printed in Great Britain - all rights reserved.
  • Kazuyuki Takahashi, Hidekazu Kozuki, Akira Onoda, Taka aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Journal of Inorganic and Organometallic Polymers 12 3-4 99 - 108 2002年12月 [査読有り][通常論文]
     
    A novel poly(carboxylate) ligand was synthesized as a ligand for a crystalline CaCO3-organic composite. Poly[1-carboxylate-2-(N-t-butylcarbamoyl)ethylene-alt-ethylene] has a 7-membered ring with an intramolecular NH ⋯ O hydrogen bond between the carboxylate group and the neighboring amide NH proton in the anionic carboxylate form. The configuration of the polymer ligand was estimated with polymer repeat-unit models, (S,S)- or (R,R)-2-(N-t-butylcarbamoyl)-cyclohexanecarboxylic acid ((S,S)- or (R,R)-TBCA) and (S,R)-2-(N-t-butylcarbamoyl)-cyclohexanecarboxylic acid ((S,R)-TBCA). The proton NMR spectum of the carboxylate anion of (S,S)- or (R,R)-TBCA exhibits a non-hydrogen bonded NH signal at 7.31 ppm in Me2SO-d6. (S,R)-TBCA shows a strongly NH ⋯ O hydrogen-bonded NH signal at 8.50 ppm. The observation of one strongly NH ⋯ O hydrogen bonded NH signal at 11.3 ppm indicates that the polymer anion has a threo-form in the zigzag polymer main chain. Moreover, a polymer ligand-CaCO3 composite was synthesized. The composite was characterized by 13C cross polarization/magic angle spinning (CP/MAS) and scanning electron microscopy (SEM). The polymer ligand stabilizes the Ca-O (carboxylate) bond in the CACO3 composite. This prevents dissociation due to pKa shifts of the NH ⋯ O hydrogen bond and controls the crystal growth toward metastable vaterite.
  • Akira Onoda, Yusuke Yamada, Taka Aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Inorganic Chemistry 41 23 6038 - 6047 2002年11月18日 [査読有り][通常論文]
     
    Two new mononuclear Ca(II) complexes with aryl dihydrogen phosphate ligands having two strategically oriented bulky amide groups, 2,6-(Ph3CCONH)2C6 H3OPO3H2 (1), including one with a phosphate monoanion, (NMe4)[CaII-{O2P(OH) OC6H3-2, 6-(NHCOCPh3)2}3(N≡CMe)3] (3), and one with a phosphate dianion, [CaII{O3POC6H3-2, 6-(NHCOCPh3)2} (H2O)3(MeOH)2] (4). Both are analogues for the NH⋯O hydrogen bonds in the active site of Ca(II)-containing phosphotransferase. Crystallographic studies of these Ca(II) complexes revealed that the amide NHs are directed to uncoordinated O atoms of the phosphates, and the IR and 1H NMR spectra indicate that strong NH⋯O hydrogen bonds are formed only in the phosphate dianion state. The ligand exchange reaction of 3 with a non-hydrogen-bonded phosphate ligand shows that the NH⋯O hydrogen bonds prevent the Ca-O bond from dissociation. A scatter plot analysis comparing the distance of a Ca-O bond with the Ca-O-P angle, the Fourier density analysis, and DFT calculations reveal that a partial degree of covalency in the Ca-O(phosphate) bonds is present.
  • Akira Onoda, Yusuke Yamada, Taka Aki Okamura, Mototsugu Doi, Hitoshi Yamamoto, Norikazu Ueyama
    Journal of the American Chemical Society 124 6 1052 - 1059 2002年02月12日 [査読有り][通常論文]
     
    Three new polynuclear Ca(II)- and Na(I) phosphate complexes with two strategically oriented bulky amide groups, 2,6-(PhCONH)2C6 H3OPO3H2, were synthesized, including one with a zigzag-chain, [CaII{O3 POC6H3-2,6- (NHCOPh)2}(H2O)4(EtOH)]n, a cyclic-octanuclear form, [CaII8 {O3POC6 H3-2,6-(NHCOPh)2}8- (O=CHNMe2)8(H2O)12], and a hexanuclear complex, (NHEt3)[Na3 {O3POC6 H3-2,6-(NHCOPh)2}2(H2O)- (MeOH)7]. X-ray crystallography revealed that all have an unsymmetric ligand position due to the bulky amide groups. A dynamic transformation of the Ca(II) zigzag-chain structure to the cyclic-octanuclear complex was induced by changing coordination of DMF molecules, which caused a reorganization of the intermolecular/intramolecular hydrogen bond network.
  • Akira Onoda, Taka Aki Okamura, Hitoshi Yamamoto, Norikazu Ueyama
    Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals 379 401 - 406 2002年 [査読有り][通常論文]
     
    Novel zigzag-chain, cyclic-octanuclear Ca- and hexanuclear Naphosphate complexes were synthesized using bulky amide aryl dihydrogen phosphate ligands. The metal complexes with bulky amides have a unique unsymmetric ligand position. The zigzag-chain structure transformed into a cyclic-octanuclear one in cooperating with the coordination of DMF molecule and reorganization of the intermolecular/intramolecular hydrogen bond networks.
  • Ueyama N, Takahasi K, Onoda A, Okamura T.-A, Yamamoto H
    Macromolecular Symposia 186 129 - 134 2002年 [査読有り][通常論文]
     
    Novel poly (carboxylates), partially amidated poly(acrylate), poly[1-carboxylate-2-(N-t-butyl)carbamoyl]ethylene-alt-ethylene}, poly[1-(N-oxy succiny1-aminometheny1)ethy lene], poly[1-(N-oxy maleny 1-aminomethnyl)ethylene] and poly [1-(N-oxyphthalyl-aminomethnyl)ethylene] with intramolecular NH-O hydrogen bond between amide NH and coordinating oxygen were synthesized as model ligands for CaCO3 biominerallization. The FE/SEM and its backscatter of the CaCO3 composite of gold colloid-conjugated poly {[1-carboxy late-2-(N-p-methylthiopheny1)carbamoy1]ethy lene-alt-ethy1-ene} indicate that the polymer ligand is located at the surface of vaterite crystals and the oriented carboxylate ligands control the CaCO3 polymorph.
  • A Onoda, T Okamura, H Yamamoto, N Ueyama
    ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 57 O1022 - O1024 2001年11月 [査読有り][通常論文]
     
    The title compound, C12H19OP4, with a bulky group, exhibits one-dimensional hydrogen-bonded chains of bifurcated P-OH . . .O=P interactions. This one-dimensional chain structure with double P-OH . . .O=P hydrogen bonds is induced by the bulky isopropyl groups.
  • Ueyama N, Inohara M, Onoda A, Ueno T, Okamura T.-A, Nakamura A
    Inorganic Chemistry 38 18 4028 - 4031 1999年 [査読有り][通常論文]
     
    Mercury(II) complexes which have a bulky cholyl amide group at the ortho or para position of benzenethiolate, Hg[S-2-{C23H36(OH)3}CONHC6H 4]2 (1) with an intramolecular NH⋯S hydrogen bond and Hg[S-4-{C23H36(OH)3)CONHC6H 4]2 (2), were synthesized to prepare an aqueous micellar solution. A hydrated Hg(II) ion was formed from the Hg(II) thiolate complexes, 1 and 2, at the ligand dissociation point (pH 4.0 and 4.9, respectively) near the pKa values (5.7 and 7.0, respectively) of the corresponding thiols. The hydrated Hg(II) ion was detected by the formation of Hg(0) species reduced with Na2S2O4 in an aqueous micellar solution. The NH⋯S hydrogen bond lowers the pKa value of the conjugated thiol to protect the Hg-S bond from dissociation by water under neutral conditions. © 1999 American Chemical Society.

書籍

  • “Artificial Metalloenzymes Containing an Organometallic Active Site”, In Bioorganometallic Chemistry: Applications in Drug Discovery, Biocatalysis, and Imaging.
    A. Onoda, T. Hayashi, M. Salmain (担当:共著)
    Wiley-VCH 2014年12月 (ISBN: 9783527335275)

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  • 人工転写システムの開発に向けた金属イオンセンサー型DNA結合タンパク質の精密制御 (日本証券奨学財団)
    2004年
  • 金属イオンセンサー機能を有する人工DNA結合タンパク質の創製 (科学技術振興会(小玉財団))
    2004年
  • 無機結晶に結合したオリゴペプチドの構造解析によるバイオミネラルの構築機構解明 (蛋白質研究奨励会)
    2003年

その他活動・業績

  • Tomoki Himiyama, Minoru Waki, Dolores Esquivel, Akira Onoda, Takashi Hayashi, Pascal Van Der Voort, Shinji Inagaki ChemCatChem 10 (21) 4908 -4913 2018年11月07日 [査読無し][通常論文]
     
    A diiron [FeFe]-hydrogenase model complex tethered with a maleimide group, FeFe1, was covalently grafted on the pore surface of a periodic mesoporous organosilica with thiol groups (SH-PMO) to form an efficient heterogeneous hydrogen (H2)-evolution catalyst FeFe1@PMO. The coordination structure of the FeFe1 complex and the ordered pore structure were almost completely preserved even after immobilization of FeFe1 on SH-PMO. The FeFe1@PMO promoted photocatalysis for H2 evolution in water containing a photosensitizer [Ru(bpy)3]2+, with a turnover number (TON) of 310 over 120 min. The TON was greater than those of an analogous homogeneous FeFe1 catalyst (TON=180) and conventional diiron complexes immobilized on solid supports (TON=6–18). The increased TON for FeFe1@PMO compared to the homogeneous FeFe1 was attributed to the improvement in the stability of the FeFe1 complex by immobilization on the pore surface of SH-PMO. A [Ru(bpy)3]2+ photosensitizer tethered with a maleimide (Ru1) was prepared and co-immobilized on FeFe1@PMO to form an all-solid-state photocatalyst FeFe1-Ru1@PMO. FeFe1-Ru1@PMO evolved H2 without the additional [Ru(bpy)3]2+ photosensitizer, suggesting efficient photoinduced electron transfer from the immobilized Ru1 to the immobilized FeFe1.
  • Alexander R. Grimm, Daniel F. Sauer, Mehdi D. Davari, Leilei Zhu, Leilei Zhu, Marco Bocola, Shunsuke Kato, Akira Onoda, Takashi Hayashi, Jun Okuda, Ulrich Schwaneberg, Ulrich Schwaneberg ACS Catalysis 8 (4) 3358 -3364 2018年04月 [査読無し][通常論文]
     
    © 2018 American Chemical Society. Incorporation of a synthetic metal catalyst into a protein scaffold yields a biohybrid catalyst, with a remarkable performance in aqueous media and the broad reaction scope of organometallic catalysts. A major challenge for efficient catalysis is the design of the interface between the protein scaffold and the metal catalyst. Until now, protein scaffolds have primarily been engineered by exchanging individual amino acids to anchor metal catalysts and alter their immediate environment. Here, cavity size engineering of the β-barrel protein nitrobindin was performed by duplicating multiple β-strands to generate an expanded variant. The approach of cavity size engineering enabled covalent incorporation of bulky catalysts at excellent coupling efficiencies and yielded excellent conversions in olefin metathesis, including ring-closing metathesis, ring-opening metathesis polymerization, and cross metathesis (conversions up to 99% and turnover numbers up to 10000).
  • Yuta Tanaka, Akira Onoda, Shin Ichi Okuoka, Tomoyuki Kitano, Koki Matsumoto, Takao Sakata, Hidehiro Yasuda, Takashi Hayashi ChemCatChem 10 (4) 743 -750 2018年02月21日 [査読無し][通常論文]
     
    © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The front cover artwork for issue 4/2018 represents research conducted in a collaboration between Osaka University (Japan) and Nippon Shokubai Co., Ltd. (Japan). The image illustrates the preparation of the Fe/N/C catalysts by pyrolysis of π-expanded Fe(Salen) precursors for the oxygen reduction reaction. See the Full Paper itself at https://doi.org/10.1002/cctc.201701629.
  • Hiroaki Kitagishi, Daiki Shimoji, Takehiro Ohta, Ryo Kamiya, Yasuhiro Kudo, Akira Onoda, Takashi Hayashi, Jean Weiss, Jennifer A. Wytko, Koji Kano Chemical Science 9 (7) 1989 -1995 2018年02月21日 [査読無し][通常論文]
     
    In mitochondria, cytochrome c oxidase (CcO) catalyses the reduction of oxygen (O2) to water by using a heme/copper hetero-binuclear active site. Here we report a highly efficient supramolecular approach for the construction of a water-soluble biomimetic model for the active site of CcO. A tridentate copper(ii) complex was fixed onto 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(iii) (FeIIITPPS) through supramolecular complexation between FeIIITPPS and a per-O-methylated β-cyclodextrin dimer linked by a (2,2′:6′,2′′-terpyridyl)copper(ii) complex (CuIITerpyCD2). The reduced FeIITPPS/CuITerpyCD2 complex reacted with O2 in an aqueous solution at pH 7 and 25 °C to form a superoxo-type FeIII-O2-/CuI complex in a manner similar to CcO. The pH-dependent autoxidation of the O2 complex suggests that water molecules gathered at the distal Cu site are possibly involved in the FeIII-O2-/CuI superoxo complex in an aqueous solution. Electrochemical analysis using a rotating disk electrode demonstrated the role of the FeTPPS/CuTerpyCD2 hetero-binuclear structure in the catalytic O2 reduction reaction.
  • Fargol Taba, Akira Onoda, Urara Hasegawa, Urara Hasegawa, Toshiaki Enoki, Yousuke Ooyama, Joji Ohshita, Takashi Hayashi ChemMedChem 13 (1) 15 -19 2018年01月08日 [査読無し][通常論文]
     
    © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Two polyamine derivatives of protoporphyrin IX (PPIX) were tested as photodynamic therapy (PDT) agents in HT29 colorectal cancer and HEP3B liver cancer cell lines. These compounds exhibit excellent singlet oxygen quantum yields and show strong in vitro PDT efficacy after 660 nm laser irradiation, whereas exogenous PPIX itself exhibits much weaker PDT effects. Confocal microscopy imaging studies reveal that a protoporphyrin derivative with eight amine moieties has excellent water solubility, and localizes mainly in the mitochondria of both HT29 and HEP3B cells, whereas the cellular distribution of a protoporphyrin derivative with four amine moieties is not as specific. This work demonstrates that polyamine moieties on macrocycles can enhance PDT efficacy by targeting mitochondria.
  • Akira Onoda, Yuta Tanaka, Koki Matsumoto, Minoru Ito, Takao Sakata, Hidehiro Yasuda, Takashi Hayashi RSC Advances 8 (6) 2892 -2899 2018年 [査読無し][通常論文]
     
    © The Royal Society of Chemistry 2018. Nonprecious metal electrocatalysts are being explored as alternatives to platinum-group metal electrocatalysts for the oxygen reduction reaction (ORR) which is required for cathode materials in fuel cells. Herein, we describe a new method for preparing bimetallic nitrogen-containing carbon catalysts with high ORR activity using π-expanded M(salen) precursors. The M/N/C and bimetallic FeM/N/C ORR catalysts were obtained by pyrolysis of a mixture of a carbon support (Vulcan XC-72R) and the metal complex as a precursor. The bimetallic FeCu catalyst prepared from Fe and Cu complexes with the N,N′-bis(2-hydroxy-1-naphthylidene)-1,2-phenylenediamine ligand (2NAPD) is found to have an onset potential of 0.87 V, which is positively shifted by 50 mV from that of the catalyst prepared from the monometallic Fe(2NAPD) complex. The FeCu/N/C catalyst promotes efficient four-electron reduction in the ORR. High-resolution transmission electron microscopy studies reveal that both Fe and Cu metals together with pyridinic nitrogen species are highly dispersed within the carbonaceous structure in FeCu/2NAPD@VC, suggesting that the N-coordinated Fe and Cu sites promote efficient four-electron reduction of O2. This new methodology facilitates design of nonprecious bimetallic carbon catalysts with excellent ORR activity.
  • Tomoki Himiyama, Naomasa Taniguchi, Shunsuke Kato, Akira Onoda, Takashi Hayashi Angewandte Chemie - International Edition 56 (44) 13618 -13622 2017年10月23日 [査読無し][通常論文]
     
    © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A unique π-expanded reaction cavity tethering a polycyclic moiety which provides a platform for substrate binding was constructed within the robust β-barrel structure of nitrobindin (NB). NB variants with cavities of different sizes and shapes are coupled with N-(1-pyrenyl)maleimide (Pyr) to prepare a series of NB-Pyr conjugates. The orientation of the pyrene moiety is fixed within the cavity by the coupling reaction. The fluorescent quenching analysis of NB-Pyr indicates that azachalcone (aza), which is a dienophile for a Diels–Alder (DA) reaction, is efficiently incorporated within the pyrene-linked reaction cavity by the aromatic interaction. The DA reaction between aza and cyclopentadiene proceeds within the reaction cavity of NB-Pyr in the presence of CuIIion in high yield and high enantio- and regioselectivity.
  • Akira Onoda, Yasunari Umeda, Takashi Hayashi Chemistry Letters 46 (12) 1818 -1821 2017年 [査読無し][通常論文]
     
    Horseradish peroxidase apoprotein (apoHRP) was immobilized on a heme-modified polythiophene film, which was electro-polymerized on an indium tin oxide surface to yield immobilized and reconstituted HRP. The HRP-immobilized electrode exhibits a 6-fold enhanced electrochemical response toward hydrogen peroxide reduction relative to having the protein randomly immobilized on the polythiophene electrode. This indicates that the insertion of the heme moiety into the heme pocket of HRP leads to an increase in the electrocatalytic current.
  • Hirofumi Harada, Akira Onoda, Takayuki Uchihashi, Hiroki Watanabe, Naoki Sunagawa, Masahiro Samejima, Kiyohiko Igarashi, Takashi Hayashi Chemical Science 8 (9) 6561 -6565 2017年 [査読無し][通常論文]
     
    Cellobiose dehydrogenase (CDH) is a dual domain flavocytochrome, which consists of a dehydrogenase (DH) domain containing a flavin adenine dinucleotide and a cytochrome (CYT) domain containing b-type heme. To directly visualize the dynamic domain motion of class-I CDH from Phanerochaete chrysosporium (PcCDH) during catalysis using high-speed atomic force microscopy, the apo-form of PcCDH was anchored to a heme-immobilized flat gold surface that can specifically fix the orientation of the CYT domain. The two domains of CDH are found to be immobile in the absence of cellobiose, whereas the addition of cellobiose triggers an interdomain flip-flop motion involving domain-domain association and dissociation. Our results indicate that dynamic motion of a dual domain enzyme during catalysis induces efficient electron transfer to an external electron acceptor.
  • Hirofumi Harada, Akira Onoda, Shiho Moriguchi, Takashi Hayashi ChemistrySelect 1 (18) 5666 -5670 2016年11月01日 [査読無し][通常論文]
     
    Photoinduced charge separation on a hybrid titanium dioxide (TiO2) surface with a gold nanoparticle (AuNP) assembly immobilized via a biotin-streptavidin interaction was visualized by Kelvin force microscopy (KFM). Biotinylated AuNP (Biot-AuNP) with a diameter of ca. 15 nm was assembled using streptavidin (STV) and the AuNP assembly was immobilized on a TiO2 surface modified with 1-(3-aminopropyl)silatrane. KFM reveals that the local contact potential difference (CPD) of dispersed AuNP, which is −17 ± 4.2 mV in the dark, undergoes a negative shift of −46 ± 3.0 mV upon UV-irradiation (λ=240-300 nm). In contrast, the AuNP assembly on the TiO2 surface exhibits a greater negative shift of −58 ± 6.0 mV of the CPD, although the CPD value of −16 ± 5.8 mV in the dark is similar to that of the dispersed AuNP. KFM visualization demonstrates that assembly of the AuNP on the TiO2 surface contributes to efficient storage of the negative charge generated by excited electrons in TiO2 during photoinduced charge separation.
  • 原田裕史, 小野田晃, 砂川直輝, 五十嵐圭日子, 林高史 錯体化学会討論会講演要旨集 65th 2015年
  • A. Onoda, K. Fukumoto, T. Hayashi JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY 19 S569 -S569 2014年03月 [査読無し][通常論文]
  • Akira Onoda, Yasunori Okamoto, Hiroshi Sugimoto, Yoshitsugu Shiro, Takashi Hayashi Inorganic Chemistry 50 (11) 4892 -4899 2011年06月06日 [査読無し][通常論文]
     
    The bacterial chemotaxis protein of Desulfovibrio vulgaris DcrH (DcrH-Hr) functions as an O2-sensing protein. This protein has a hemerythrin-like domain that includes a nonheme diiron center analogous to the diiron center of the hemerythrin (Hr) family. Interestingly, the O2 affinity of DcrHHr is 3.3 × 106 M-1, a value 25-fold higher than that of the Pectinaria gouldii Hr. This high affinity arises from the fast association of the O2 ligand with DcrH-Hr (kon = 5.3 × 10 8 M-1 s-1), which is made possible by a hydrophobic tunnel that accelerates the passage of the O2 ligand to the diiron site. Furthermore, the autoxidation kinetics indicate that the rate of autoxidation of DcrH-Hr is 54-fold higher than that of P. gouldii Hr, indicating that the oxy form of DcrH-Hr is not stable toward autoxidation. More importantly, a mixed-valent state, semimetR, which was spectroscopically observed in previous Hr studies, was found to be stable for over 1 week and isolable in the case of DcrH-Hr. The high-resolution crystal structures of the semimetR- (1.8 Å) and met-DcrH-Hr (1.4 Å) indicate that the semimetR- and met- DcrH-Hr species have very similar coordination geometry at the diiron site. © 2011 American Chemical Society.
  • Akira Onoda, Yasunori Okamoto, Hiroshi Sugimoto, Yoshitsugu Shiro, Takashi Hayashi Inorganic Chemistry 50 (11) 4892 -4899 2011年06月06日 [査読無し][通常論文]
     
    The bacterial chemotaxis protein of Desulfovibrio vulgaris DcrH (DcrH-Hr) functions as an O2-sensing protein. This protein has a hemerythrin-like domain that includes a nonheme diiron center analogous to the diiron center of the hemerythrin (Hr) family. Interestingly, the O2 affinity of DcrHHr is 3.3 × 106 M-1, a value 25-fold higher than that of the Pectinaria gouldii Hr. This high affinity arises from the fast association of the O2 ligand with DcrH-Hr (kon = 5.3 × 10 8 M-1 s-1), which is made possible by a hydrophobic tunnel that accelerates the passage of the O2 ligand to the diiron site. Furthermore, the autoxidation kinetics indicate that the rate of autoxidation of DcrH-Hr is 54-fold higher than that of P. gouldii Hr, indicating that the oxy form of DcrH-Hr is not stable toward autoxidation. More importantly, a mixed-valent state, semimetR, which was spectroscopically observed in previous Hr studies, was found to be stable for over 1 week and isolable in the case of DcrH-Hr. The high-resolution crystal structures of the semimetR- (1.8 Å) and met-DcrH-Hr (1.4 Å) indicate that the semimetR- and met- DcrH-Hr species have very similar coordination geometry at the diiron site. © 2011 American Chemical Society.
  • Koji Oohora, Akira Onoda, Hiroaki Kitagishi, Hiroyasu Yamaguchi, Akira Harada, Takashi Hayashi Chemical Science 2 (6) 1033 -1038 2011年06月 [査読無し][通常論文]
     
    Artificial self-assembling systems comprised of proteins have the potential not only for mimicking naturally occurring protein clusters but also for creating functionalized supramolecular polymers. Here we report a new type of a supramolecular protein polymer which utilizes the original character and reactivity of the monomer protein. Myoglobin, an oxygen storage hemoprotein, was chosen as the monomer unit and was provided with an externally-attached heme on the protein surface which drives the formation of the fibrous supramolecular assembly through successive interprotein interactions between the external heme and the protein matrix. This assembly governed by myoglobin characteristics shows chemically-responsive stability and can be converted into extremely large protein clusters via cross-linking. Interestingly, the assembly retains the oxygen storage function. Our present system can be used for construction of smart nanobiomaterials using various hemoproteins. © The Royal Society of Chemistry 2011.
  • Yohei Sano, Akira Onoda, Rie Sakurai, Hiroaki Kitagishi, Takashi Hayashi JOURNAL OF INORGANIC BIOCHEMISTRY 105 (5) 702 -708 2011年05月 [査読無し][通常論文]
     
    Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the a-domain of MT (MT alpha) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible. CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTa matrix with Fe-4(II)-MT alpha and Co-4(II)-MT alpha species existing in water. Furthermore, the Fe-4(II)-MT alpha species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with Fe-4(II)-MT alpha (1:1) was found to proceed with a conversion of 98% over a period of 6 h at 25 degrees C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix. (C) 2011 Elsevier Inc. All rights reserved.
  • Yohei Sano, Akira Onoda, Rie Sakurai, Hiroaki Kitagishi, Takashi Hayashi JOURNAL OF INORGANIC BIOCHEMISTRY 105 (5) 702 -708 2011年05月 [査読無し][通常論文]
     
    Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the a-domain of MT (MT alpha) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible. CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTa matrix with Fe-4(II)-MT alpha and Co-4(II)-MT alpha species existing in water. Furthermore, the Fe-4(II)-MT alpha species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with Fe-4(II)-MT alpha (1:1) was found to proceed with a conversion of 98% over a period of 6 h at 25 degrees C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix. (C) 2011 Elsevier Inc. All rights reserved.
  • Yohei Sano, Akira Onoda, Takashi Hayashi CHEMICAL COMMUNICATIONS 47 (29) 8229 -8231 2011年 [査読無し][通常論文]
     
    The diiron carbonyl cluster is held by a native CXXC motif, which includes Cys14 and Cys17, in the cytochrome c sequence. It is found that the diiron carbonyl complex works well as a catalyst for H(2) evolution. It has a TON of similar to 80 over 2 h at pH 4.7 in the presence of a Ru-photosensitizer and ascorbate as a sacrificial reagent in aqueous media.
  • Koji Oohora, Akira Onoda, Hiroaki Kitagishi, Hiroyasu Yamaguchi, Akira Harada, Takashi Hayashi CHEMICAL SCIENCE 2 (6) 1033 -1038 2011年 [査読無し][通常論文]
     
    Artificial self-assembling systems comprised of proteins have the potential not only for mimicking naturally occurring protein clusters but also for creating functionalized supramolecular polymers. Here we report a new type of a supramolecular protein polymer which utilizes the original character and reactivity of the monomer protein. Myoglobin, an oxygen storage hemoprotein, was chosen as the monomer unit and was provided with an externally-attached heme on the protein surface which drives the formation of the fibrous supramolecular assembly through successive interprotein interactions between the external heme and the protein matrix. This assembly governed by myoglobin characteristics shows chemically-responsive stability and can be converted into extremely large protein clusters via cross-linking. Interestingly, the assembly retains the oxygen storage function. Our present system can be used for construction of smart nanobiomaterials using various hemoproteins.
  • Akira Onoda, Hirokazu Nagai, Satoe Koga, Takashi Hayashi BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 83 (4) 375 -377 2010年04月 [査読無し][通常論文]
     
    Artificial prosthetic groups tethering a polyamine moiety at the terminal of two peripheral heme propionate side chains as a molecular interface were inserted into apocytochrome 6567 to provide positively charged reconstituted hemoproteins, which exhibit a strong binding with double-stranded DNA.
  • Akira Onoda, Hirokazu Nagai, Satoe Koga, Takashi Hayashi BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 83 (4) 375 -377 2010年04月 [査読無し][通常論文]
     
    Artificial prosthetic groups tethering a polyamine moiety at the terminal of two peripheral heme propionate side chains as a molecular interface were inserted into apocytochrome 6567 to provide positively charged reconstituted hemoproteins, which exhibit a strong binding with double-stranded DNA.
  • Akira Onoda, Yuichi Ueya, Taiki Sakamoto, Taro Uematsu, Takashi Hayashi CHEMICAL COMMUNICATIONS 46 (48) 9107 -9109 2010年 [査読無し][通常論文]
     
    Interaction of apohemoprotein with a covalently immobilized heme moiety onto a gold nanoparticle surface resulted in supramolecular hemoprotein-gold nanoparticle conjugates. The addition of an apohemoprotein dimer further led to a densely-packed hemoprotein-gold nanoparticle assembly, which was visualized by TEM and AFM measurements.
  • Hirokazu Nagai, Akira Onoda, Takashi Matsuo, Takashi Hayashi Supramol. Chem. 22 (1) 57 -64 2010年 [査読無し][通常論文]
     
    Two different types of artificial glycosylated haemins (glycohaemins), in which a monosaccharide (galactose) or a disaccharide (lactobionic acid, 4-O-beta-galactopyranosyl-D-gluconic acid) was introduced at the terminals of the two haempropionate side chains, were synthesised to serve as a designed interface on the myoglobin surface. These glycohaemins were successfully inserted into apomyoglobin to yield an artificial glycoprotein by the conventional method. The interprotein interaction between the reconstituted myoglobin and peanut agglutinin lectin (PNA), a beta-galactose-recognising protein, was confirmed by two different assay systems, i.e. a fluorometric assay using the fluorescein isothiocyanate-labelled lectin and an ELISA-like assay using the peroxidase-labelled lectin. The results revealed that each myoglobin reconstituted with the glycohaemin makes a complex with PNA, in which the glycoprotein with the disaccharides showed a higher binding affinity with the lectin compared to the glycoprotein with the monosaccharides, suggesting that the binding property clearly depends on the deposited carbohydrate surface on the myoglobin.
  • Akira Onoda, Yuichi Ueya, Taiki Sakamoto, Taro Uematsu, Takashi Hayashi CHEMICAL COMMUNICATIONS 46 (48) 9107 -9109 2010年 [査読無し][通常論文]
     
    Interaction of apohemoprotein with a covalently immobilized heme moiety onto a gold nanoparticle surface resulted in supramolecular hemoprotein-gold nanoparticle conjugates. The addition of an apohemoprotein dimer further led to a densely-packed hemoprotein-gold nanoparticle assembly, which was visualized by TEM and AFM measurements.
  • Shinya Ariyasu, Akira Onoda, Ryota Sakamoto, Takeshi Yamamura Bioconjugate Chemistry 20 (12) 2278 -2285 2009年12月16日 [査読無し][通常論文]
     
    The complementary recognition of base pairs (bp) is the major strategy in the "DNA lithography" of gold (Au) clusters or nanoparticles, where single-stranded DNAs sulfurized at their termini are generally used to bind Au clusters or nanoparticles. In this report, we discuss a new material that can be used to locate Au clusters on the desired positions of DNA. For this purpose, we combined a two-domain zinc finger (ZF) and the analogue of α domain of rat's liver metallothionein (MT) to utilize the DNA-recognizing ability of ZF motifs and the heavy-metal binding ability of MTs, and prepared an artificial fusion protein, ZFZF-MTRα (1). Titration experiments monitored by absorption and circular dichroism spectroscopies, as well as an electrophoretic mobility shift assay and quantification using 5,5′-dithiobis(2- nitrobenzoic acid), clarified that (1) the ZF domain traps two divalent metal ions to fold in a ZF structure with M(Cys)2(His)2 (M = Co, Zn, and Cd) coordination units, (2) the MT domain traps metal ions to form clusters (Cd2+ particularly forms a Cd4(Cys)9 cluster) without interfering with the folding of the ZF domain, and (3) 1 recognizes the 5′-GGGGGG-3′ (G6) bp sequence in the presence of Zn2+ based on the amino acid sequence encoded in the ZF domain. The titration of Au11(PPh3)8Cl 3 (Au11) into the solution of 1 in the presence of Zn2+ revealed that the MT domain strongly binds the Au11 cluster with a 1:1 ratio, and a Au11-containing conjugate, ZF(Zn)ZF(Zn)-MTR(Au11) was obtained. Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy showed that this conjugate maintains an Au11 core in the form of Au11(PPh 3)4(S-Cys)6 without disturbing the folding nature of the ZF domain. ZF(Zn)ZF(Zn)-MTα(Au11) recognizes the bp sequence G6 with Kd1 = 450 nM, while simultaneously forming a dimer on the DNA with Kd2 = 200 nM. TEM experiments showed that the conjugates form parallelograms or triangles (defective parallelograms) on a double crossover (dx) DNA, according to the positions of G6 encoded in the dx DNA. © 2009 American Chemical Society.
  • Akira Onoda, Takako Suzuki, Hiroaki Ishizuka, Rumiko Sugiyama, Shinya Ariyasu, Takeshi Yamamura JOURNAL OF PEPTIDE SCIENCE 15 (12) 832 -841 2009年12月 [査読無し][通常論文]
     
    It is well known that the functions of metalloproteins generally originate from their metal-binding motifs. However, the intrinsic nature of individual motifs remains unknown, particularly the details about metal-binding effects on the folding of motifs; the converse is also unknown, although there is no doubt that the motif is the core of the reactivity for each metalloprotein. In this study, we focused our attention on the zinc-binding motif of the metzincin clan family, HEXXHXXGXXH; this family contains the general zinc-binding sequence His-Glu-Xaa-Xaa-His (HEXXH) and the extended GXXH region. We adopted the motif sequence of stromelysin-1 and investigated the folding properties of the Trp-labeled peptides WAHEIAHSLGLFHA (STR-W1), AWHEIAHSLGLFHA (STR-W2), AHEIAHSLGWFHA (STR-W11), and AHEIAHSLGLFHWA (STR-W14) in the presence and absence of zinc ions in hydrophobic micellar environments by circular dichroism (CD) measurements. We accessed successful incorporation of these zinc peptides into micelles using quenching of Trp fluorescence. Results of CD studies indicated that two of the Trp-incorporated peptides, STR-W1 and STR-W14, exhibited helical folding in the hydrophobic region of cetyltrimethylammonium chloride micelle. The NMR structural analysis of the apo STR-W14 revealed that the conformation in the C-terminus GXXH region significantly differred between the apo state in the micelle and the reported Zn-bound state of stromelysin-1 in crystal structures. The structural analyses of the qualitative Zn-binding properties of this motif peptide provide an interesting Zn-binding mechanism: the minimum consensus motif in the metzincin clan, a basic zinc-binding motif with an extended GXXH region, has the potential to serve as a preorganized Zn binding scaffold in a hydrophobic environment. Copyright (C) 2009 European Peptide Society and John Wiley & Sons, Ltd.
  • Shinya Ariyasu, Akira Onoda, Ryota Sakamoto, Takeshi Yamamura BIOCONJUGATE CHEMISTRY 20 (12) 2278 -2285 2009年12月 [査読無し][通常論文]
     
    The complementary recognition of base pairs (bp) is the major strategy in the "DNA lithography" of gold (Au) clusters or nanoparticles, where single-stranded DNAs sulfurized at their termini are generally used to bind Au Clusters or nanoparticles. In this report, we discuss a new material that can be used to locate Au clusters on the desired positions of DNA. For this purpose, we combined a two-domain zinc finger (ZF) and the analogue of alpha domain of rat's liver metallothionein (MT) to utilize the DNA-recognizing ability of ZF motifs and the heavy-metal binding ability of MTs, and prepared an artificial fusion protein, ZFZF-MT alpha (1). Titration experiments monitored by absorption and circular dichroism spectroscopies, as well as an electrophoretic mobility shift assay and quantification using 5,5'-dithiobis(2-nitrobenzoic acid), clarified that (1) the ZF domain traps two divalent metal ions to fold in a ZF structure with M(Cys)(2)(HiS)(2) (M = Co, Zn, and Cd) coordination units, (2) the MT domain traps metal ions to form clusters (Cd(2+) particularly forms a Cd(4)(Cys)(9) cluster) without interfering with the folding of the ZF domain, and (3) 1 recognizes the 5'-GGGGGG-3' (GO bp sequence in the presence of Zn(2+) based on the amino acid sequence encoded in the ZF domain. The titration of Au(11)(PPh(3))(9)Cl(3) (Au11) into the solution of 1 in the presence of Zn(2+) revealed that the MT domain strongly binds the Au11 cluster with a 1:1 ratio, and a Au(11)-containing conjugate, ZF(Zn)ZF(Zn)-MT alpha(Au(11)) was obtained. Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy showed that this conjugate maintains an Au(11) core in the form of Au(11)(PPh(3))(4)(S-Cys)(6) without disturbing the folding nature of the ZF domain. ZF(Zn)ZF(Zn)-MT alpha(Au(11)) recognizes the bp sequence G(6) with K(d1) = 450 nM, while simultaneously forming a dimer on the DNA with K(d2) = 200 nM. TEM experiments showed that the conjugates form parallelograms or triangles (defective parallelograms) on a double crossover (dx) DNA, according to the positions of G(6) encoded in the dx DNA.
  • Akira Onoda, Takako Suzuki, Hiroaki Ishizuka, Rumiko Sugiyama, Shinya Ariyasu, Takeshi Yamamura JOURNAL OF PEPTIDE SCIENCE 15 (12) 832 -841 2009年12月 [査読無し][通常論文]
     
    It is well known that the functions of metalloproteins generally originate from their metal-binding motifs. However, the intrinsic nature of individual motifs remains unknown, particularly the details about metal-binding effects on the folding of motifs; the converse is also unknown, although there is no doubt that the motif is the core of the reactivity for each metalloprotein. In this study, we focused our attention on the zinc-binding motif of the metzincin clan family, HEXXHXXGXXH; this family contains the general zinc-binding sequence His-Glu-Xaa-Xaa-His (HEXXH) and the extended GXXH region. We adopted the motif sequence of stromelysin-1 and investigated the folding properties of the Trp-labeled peptides WAHEIAHSLGLFHA (STR-W1), AWHEIAHSLGLFHA (STR-W2), AHEIAHSLGWFHA (STR-W11), and AHEIAHSLGLFHWA (STR-W14) in the presence and absence of zinc ions in hydrophobic micellar environments by circular dichroism (CD) measurements. We accessed successful incorporation of these zinc peptides into micelles using quenching of Trp fluorescence. Results of CD studies indicated that two of the Trp-incorporated peptides, STR-W1 and STR-W14, exhibited helical folding in the hydrophobic region of cetyltrimethylammonium chloride micelle. The NMR structural analysis of the apo STR-W14 revealed that the conformation in the C-terminus GXXH region significantly differred between the apo state in the micelle and the reported Zn-bound state of stromelysin-1 in crystal structures. The structural analyses of the qualitative Zn-binding properties of this motif peptide provide an interesting Zn-binding mechanism: the minimum consensus motif in the metzincin clan, a basic zinc-binding motif with an extended GXXH region, has the potential to serve as a preorganized Zn binding scaffold in a hydrophobic environment. Copyright (C) 2009 European Peptide Society and John Wiley & Sons, Ltd.
  • Akira Onoda, Masahiro Igarashi, Satoshi Naganawa, Kiyomi Sasaki, Shinya Ariyasu, Takeshi Yamamura BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 82 (10) 1280 -1286 2009年10月 [査読無し][通常論文]
     
    Neutral zinc porphyrin containing flexible alkyl linker, 5-[4-(5-hydroxypentyloxy)phenyl]-10,15,20-tri-p-tolyl-porphyrinatozinc, was attached to the 5' ends of 20- and 30-bp oligodeoxynucleotides (ODN) by solid-phase synthesis. Zinc porphyrin-modified double-stranded DNA (dsDNAs), which included dsDNAs with porphyrin moieties on one end and on both ends (ZnPor-ds20, ds20-ZnPor, ZnPor-ds20-ZnPor, ZnPor-ds30, ds30-ZnPor, and ZnPor-ds30-ZnPor), were successfully prepared and were analyzed by variable-temperature UV-vis spectroscopy and CD measurements to elucidate the interaction behavior of the porphyrin ring. Detailed investigation revealed that the zinc porphyrin-DNA conjugates exhibited intra-duplex porphyrin-ODN interaction in a low-salt condition and inter-duplex porphyrin-porphyrin interaction in a high-salt condition.
  • Akira Onoda, Masahiro Igarashi, Satoshi Naganawa, Kiyomi Sasaki, Shinya Ariyasu, Takeshi Yamamura BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 82 (10) 1280 -1286 2009年10月 [査読無し][通常論文]
     
    Neutral zinc porphyrin containing flexible alkyl linker, 5-[4-(5-hydroxypentyloxy)phenyl]-10,15,20-tri-p-tolyl-porphyrinatozinc, was attached to the 5' ends of 20- and 30-bp oligodeoxynucleotides (ODN) by solid-phase synthesis. Zinc porphyrin-modified double-stranded DNA (dsDNAs), which included dsDNAs with porphyrin moieties on one end and on both ends (ZnPor-ds20, ds20-ZnPor, ZnPor-ds20-ZnPor, ZnPor-ds30, ds30-ZnPor, and ZnPor-ds30-ZnPor), were successfully prepared and were analyzed by variable-temperature UV-vis spectroscopy and CD measurements to elucidate the interaction behavior of the porphyrin ring. Detailed investigation revealed that the zinc porphyrin-DNA conjugates exhibited intra-duplex porphyrin-ODN interaction in a low-salt condition and inter-duplex porphyrin-porphyrin interaction in a high-salt condition.
  • Takeshi Yamamura, Shingo Suzuki, Tomotaka Taguchi, Akira Onoda, Toshiaki Kamachi, Ichiro Okura JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (33) 11719 -11726 2009年08月 [査読無し][通常論文]
     
    The application of low-flux sunlight begins with the synthesis of effective antenna systems. This requires the development of dye integrates with optimized dye orientation for effective energy transfer. We here report a series of peptide-linked porphyrin arrays, denoted by Boc-(Por(Zn,S))-OBut (n = 2, 4, and 8), that change their dye orientation to increase fluorescence responsively to additive reagents. The B-band absorption (AB) regions of the arrays show blue shifts (dimer, 407.6 nm; tetramer, 408.2 nm; octamer, 407.8 nm) in organic solvents as compared to that of Boc-Por(Zn,S)-OBut (monomer, 422.6 nm) and the fluorescence yield Phi' of the arrays decreases with increasing n, obeying the relationship Phi' = 0.03/n(1.5); however, the arrays are tuned up in fluorescence emission by the addition of 1,2-diaminoethane (en). The addition of a sufficient amount of en increases the fluorescence of the porphyrins in monomer, dimer, tetramer, and octamer by similar to 5, similar to 12, similar to 12, and >730 times, respectively, when compared with that observed in the absence of en. This also causes asymptotic red shifts in absorption (AB) bands (B-band lambda(max): 410 to 429-430 nm), as well as changes in circular dichroism (CD) spectra, and makes porphyrins approach new mutual asymmetric orientations. Our results show the potentiality of the tunable dye polymers that are a posteriori optimized in dye orientation and fluorescence emission by additive reagents for the development of effective light-harvesting materials.
  • Takeshi Yamamura, Shingo Suzuki, Tomotaka Taguchi, Akira Onoda, Toshiaki Kamachi, Ichiro Okura JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (33) 11719 -11726 2009年08月 [査読無し][通常論文]
     
    The application of low-flux sunlight begins with the synthesis of effective antenna systems. This requires the development of dye integrates with optimized dye orientation for effective energy transfer. We here report a series of peptide-linked porphyrin arrays, denoted by Boc-(Por(Zn,S))-OBut (n = 2, 4, and 8), that change their dye orientation to increase fluorescence responsively to additive reagents. The B-band absorption (AB) regions of the arrays show blue shifts (dimer, 407.6 nm; tetramer, 408.2 nm; octamer, 407.8 nm) in organic solvents as compared to that of Boc-Por(Zn,S)-OBut (monomer, 422.6 nm) and the fluorescence yield Phi' of the arrays decreases with increasing n, obeying the relationship Phi' = 0.03/n(1.5); however, the arrays are tuned up in fluorescence emission by the addition of 1,2-diaminoethane (en). The addition of a sufficient amount of en increases the fluorescence of the porphyrins in monomer, dimer, tetramer, and octamer by similar to 5, similar to 12, similar to 12, and >730 times, respectively, when compared with that observed in the absence of en. This also causes asymptotic red shifts in absorption (AB) bands (B-band lambda(max): 410 to 429-430 nm), as well as changes in circular dichroism (CD) spectra, and makes porphyrins approach new mutual asymmetric orientations. Our results show the potentiality of the tunable dye polymers that are a posteriori optimized in dye orientation and fluorescence emission by additive reagents for the development of effective light-harvesting materials.
  • Shinya Ariyasu, Akira Onoda, Ryota Sakamoto, Takeshi Yamamura Dalton Transactions (19) 3742 -3747 2009年 [査読無し][通常論文]
     
    The stoichiometrically controlled complexation of abiological inorganic clusters with proteins is a challenging task that enables us to combine the functions of inorganic clusters with those of biological systems on the basis of chemical characterisation. In this study, we synthesised a 1:1 conjugate between Au 11(PPh 3) 8Cl 3 (Au11) and CGMTIIα, where Au11 is the smallest cluster, which is situated on the boundary of molecules and nanoparticles, having discrete electronic states and exhibiting Coulomb blockade on the other hand, CGMTIIα is a twelve-cysteine (Cys)-containing peptide consisting of the α-domain of rat liver metallothionein II (MTIIα) - a heavy metal-binding protein - and an addendum, cysteine-glycine (CG). The Cys residue of the N-terminus is used as a site for elongation by the native chemical ligation (NCL) method. Titration experiments monitored by circular dichroism spectroscopy indicate that CGMTIIα reacts with Au11 in a ratio of 1:1. The product exhibits a negative Cotton effect at 222 nm, indicating the formation of a short a-helix. The composition of this hybrid module is quantified as Au 11(PPh 3) 4(S-Cys) 6 by transmission electron microscopy (core size observation), energy-dispersive X-ray spectroscopy (elemental analysis), Ellman test (uncoordinated Cys residues), and high-performance liquid chromatography (quantification of eliminated PPh 3). These results, as well as those obtained from the simulations of Au 4f X-ray photoelectron spectra, suggest that the Au cluster of this product is Au 11(PPh 3) 4(S-Cys) 6. We also prepared F3F3-CGMTIIα, where F3F3 is a zinc finger peptide with two domains, in order to demonstrate the applicability of the NCL method to the elongation of CGMTIIα. F3F3-CGMTIIα also reacts with Au11 to yield a 1:1 conjugate without interfering in the folding of the zinc finger. © 2009 The Royal Society of Chemistry.
  • A Onoda, N Shimazu, N Arai, H Yamamoto, T Yamamura ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 229 U1068 -U1068 2005年03月 [査読無し][通常論文]
  • A Onoda, H Yamamoto ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 225 U22 -U22 2003年03月 [査読無し][通常論文]
  • A Onoda, Y Yamada, T Okamura, H Yamamoto, N Ueyama Inorganic Chemistry 41 (23) 6038 -6047 2002年11月 [査読無し][通常論文]
     
    Two new mononuclear Ca(II) complexes with aryl dihydrogen phosphate ligands having two strategically oriented bulky amide groups, 2,6-(Ph3CCONH)(2)C6H3OPO3H2 (1), including one with a phosphate monoanion, (NMe4)[Ca-II-{O2P(OH)OC6H3-2,6-(NHCOCPh3)(2)}(3)(Nequivalent toCMe)(3)] (3), and one with a phosphate dianion, [Ca-II{O3POC6H3-2,6-(NHCOCPh3)(2)}(H2O)(3)(MeOH)(2)] (4). Both are analogues for the (NHO)-O-. . . hydrogen bonds in the active site of Ca(II)-containing phosphotransferase. Crystallographic studies of these Ca(II) complexes revealed that the amide NHs are directed to uncoordinated 0 atoms of the phosphates, and the IR and H-1 NMR spectra indicate that strong (NHO)-O-. . . hydrogen bonds are formed only in the phosphate dianion state. The ligand exchange reaction of 3 with a non-hydrogen-bonded phosphate ligand shows that the (NHO)-O-. . . hydrogen bonds prevent the Ca-O bond from dissociation. A scatter plot analysis comparing the distance of a Ca-O bond with the Ca-O-P angle, the Fourier density analysis, and DFT calculations reveal that a partial degree of covalency in the Ca-O(phosphate) bonds is present.
  • A Onoda, Y Yamada, T Okamura, M Doi, H Yamamoto, N Ueyama JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 (6) 1052 -1059 2002年02月 [査読無し][通常論文]
     
    Three new polynuclear Ca(II)- and Na(I) phosphate complexes with two strategically oriented bulky amide groups, 2,6-(PhCONH)(2)C(6)H(3)OPO(3)H(2), were synthesized, including one with a zigzag-chain, [Ca(II){O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(H(2)O)(4)(EtOH)](n), a cyclic-octanuclear form, [Ca(II)8{O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(8)-(O=CHNMe(2))(8)(H(2)O)(12)], and a hexanuclear complex, (NHEt(3))[Na(3){O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(2)(H(2)O)-(MeOH)(7)]. X-ray crystallography revealed that all have an unsymmetric ligand position due to the bulky amide groups. A dynamic transformation of the Ca(II) zigzag-chain structure to the cyclic-octanuclear complex was induced by changing coordination of DMF molecules, which caused a reorganization of the intermolecular/intramolecular hydrogen bond network.
  • A Onoda, Y Yamada, T Okamura, M Doi, H Yamamoto, N Ueyama JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 (6) 1052 -1059 2002年02月 [査読無し][通常論文]
     
    Three new polynuclear Ca(II)- and Na(I) phosphate complexes with two strategically oriented bulky amide groups, 2,6-(PhCONH)(2)C(6)H(3)OPO(3)H(2), were synthesized, including one with a zigzag-chain, [Ca(II){O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(H(2)O)(4)(EtOH)](n), a cyclic-octanuclear form, [Ca(II)8{O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(8)-(O=CHNMe(2))(8)(H(2)O)(12)], and a hexanuclear complex, (NHEt(3))[Na(3){O(3)POC(6)H(3)-2,6-(NHCOPh)(2)}(2)(H(2)O)-(MeOH)(7)]. X-ray crystallography revealed that all have an unsymmetric ligand position due to the bulky amide groups. A dynamic transformation of the Ca(II) zigzag-chain structure to the cyclic-octanuclear complex was induced by changing coordination of DMF molecules, which caused a reorganization of the intermolecular/intramolecular hydrogen bond network.
  • Inorganic Chemistry 41 (6038-6047) 2002年 [査読無し][通常論文]
  • UEYAMA N, KOZUKI H, DOI M, YAMADA Y, TAKAHASHI K, ONODA A, OKAMURA T, YAMAMOTO H Macromolecules 34 (8) 2607 -2614 2001年04月 [査読無し][通常論文]
     
    Alternately amidated poly(1-carboxylate-3-N-alkylamidotetramethylene)s (alkyl = t-Bu, n-Bu) were synthesized from poly(acrylic anhydride) and alkylamines as ligands for Ca(II) complexes. The anion form of the alternately amidated polycarboxylates possesses an NH···O hydrogen bond between the carboxylate oxygen and the adjacent amide NH. The reinforcement of Ca-O bond strength by the NH···O hydrogen bond, upon the mineralization of calcium carbonate, is maintained at the interface between crystalline CaCO3 and the polymer ligands because it prevents the removal of the alternately amidated poly(1-carboxylate-3-N-alkylamidotetramethylene) ligand from the crystalline CaCO3 under neutral conditions. Under the same conditions, a commercial poly(acrylate) ligand readily releases Ca(II) ion to separate from the surface of the crystal by hydrolysis with water. The binding carboxylate ligand 13C on calcium carbonate is detectable using solid-state 13C CP/MAS spectroscopy.
  • ONODA A, YAMADA Y, DOI M, OKAMURA T, UEYAMA N Inorganic Chemistry 40 (3) 516 -521 2001年01月29日 [査読無し][通常論文]
     
    The novel intramolecularly NH···O hydrogen-bonded Ca(II)-aryl sulfonate complex, [Ca2 (SO3-2-t-BuCONHC6H4)2 (H2O)4]n (2-t-BuCONHC6H4SO3)2n (1), sulfonate anion, (HNEt3)(SO33-2-t-BuCONHC6H4) (2a), (PPh4)(SO3-2-t-BuCONHC6H4) (2b), (n-Bu4N)(SO3-2-t-BuCONHC6H4) (2c), and sulfonic acid, 2-t-BuCONHC6H4SO3H (3), were synthesized. The structures of l, 2a, and 2b depict the presence of the formation of NH···O hydrogen bonds between the amide NH and S-O oxygen for a series of compounds as determined by IR and 1H NMR analyses both in the solid state and in the solution state. Thus, the NH···O hydrogen bonds with neutral amide groups are available for investigation of the electronic state of the O- anion. The combined data from the IR and 1H NMR spectra indicate that the sulfonic acid, sulfonate anion, and Ca(II) complex have a substantially weak intramolecular NH···O hydrogen bond between the SO3 oxygen and amide NH. In the detailed comparison with the intense NH···O hydrogen bonds for the carboxylate, weak NH···O hydrogen bonds for sulfonate is due to the strong conjugation of the SO3- group with the lower nucleophilicity.
  • One-divevdional P-olt…O=P hydrogen bonds restricted by the bulky ligand, 2,6-diisopropye benzene dihydrogen phosphate
    Acta. Cryctallogr. E 57 (01022-01024) 2001年 [査読無し][通常論文]
  • One-divevdional P-olt…O=P hydrogen bonds restricted by the bulky ligand, 2,6-diisopropye kenzene dihydrogen phosphate
    Acta. Cryctallogr. E 57 (01022-01024) 2001年 [査読無し][通常論文]
  • A Onoda, T Okamura, N Ueyama, A Nakamura ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 219 U853 -U853 2000年03月 [査読無し][通常論文]
  • A Onoda, T Okamura, Norikazu, Ueyama, A Nakamura JOURNAL OF INORGANIC BIOCHEMISTRY 74 (1-4) 254 -254 1999年04月 [査読無し][通常論文]
  • UEYAMA N, TAKEDA J, YAMADA Y, ONODA A, OKAMURA T, NAKAMURA A Inorganic Chemistry 38 (3) 475 -478 1999年 [査読無し][通常論文]
     
    A novel dinuclear calcium complex, [Ca2{(2-OCO-3-CH3C6H3NHCO) 2C(CH3)2}2(CH3OH) 6] (1), was synthesized as a structural model of 8-coordinated Ca(II) ions in the double calcium-binding site of thermolysin. The complex has four NH⋯O hydrogen bonds between the amide NH and the carboxylate oxygen anion. Two types of bridging coordination of the carboxylate ligand to Ca(II) were found in 1. The amide NH forms a strong NH⋯O hydrogen bond with the anionic oxygen of the two carboxylate oxygens. A ligand-exchange reaction between the dinuclear calcium complex and eight equimolar amounts of 2,4,6-trimethylbenzoic acid or 2-CH3-6-t-BuCONHC6H3COOH indicates that the NH⋯O hydrogen bond prevents the dissociation of the Ca-O bond. © 1999 American Chemical Society.

特許

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    研究期間 : 2019年04月 -2021年03月 
    代表者 : 小野田 晃
     
    本研究では、多彩な反応性を示す金属錯体触媒と、精緻な反応場を提供するバレル型タンパク質の融合により、アシンメトリー配位圏を有するバイオハイブリッド触媒を構築し、従来の金属錯体や酵素にはない新たな位置選択性や官能基選択性を付与した合成反応の開拓に取り組んだ。反応性の高いRh錯体を固定化したバイオハイブリッド触媒を活用し、位置選択的な炭素-炭素結合形成反応、また、バレル空孔内に芳香環拡張型のアシンメトリー配位圏を構築し、不斉Diels-Alder 反応を実証した。タンパク質には、強固なベータバレル構造を有するニトロバインディンの疎水空孔を活用して、様々な金属錯体触媒を共有結合により残基選択的に固定化したバイオハイブリッド触媒を開発してきた成果を踏まえて、ペンタメチルシクロペンタジエニル配位子をもつRh(III)錯体を選択し、マレイミドを導入した錯体とニトロバインディンの疎水空孔内のシステインを共有結合的に連結可能な手法を確立した。ジチオリン酸配位子で空配位座を保護したRh(III)錯体をタンパク質に連結後、硝酸銀の添加により、Rh(III)錯体を活性化する手法である。この手法により調製したバイオハイブリッド触媒は、硝酸銀存在下、フェニルオキシム及びアルキンの付加環化反応において触媒活性を示すことを明らかにした。ニトロバインディンの疎水性空孔にグルタミン酸を導入することによって、触媒活性が向上することを見出しており、Rh(III)錯体近傍のアシンメトリー空間の構築を成功した。
  • 金属錯体を微生物の細胞表面に固定化した高選択的バイオハイブリッド触媒系の開発
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 小野田 晃
     
    社会から要請される複雑な物質群を高効率かつ選択的に変換する触媒系を開拓することは、最重要課題の一つである。金属錯体触媒に、生物がもつ多様な分子環境を融合すれば、未踏の選択性を達成すると期待される。本研究は、多彩な反応性をもつ金属錯体触媒と、精緻かつ多様な反応場を提供するバレル型タンパク質を融合したバイオハイブリッド触媒を構築し、従来にはない位置選択性・官能基選択性・基質選択性を付与した触媒系を開拓することが目的である。さらに、バイオハイブリッド触媒部位を細胞表面提示した人工微生物触媒を作製し、金属錯体の反応場と網羅的かつ高速に探索可能な実験室進化の手法と組み合わせ、タンパク質反応場を最適化し、困難な反応選択性を示す触媒を開拓する。本年度は、反応性の高いシクロペンタジエニルロジウム錯体を固定化したバイオハイブリッド触媒を活用し、非対称内部アルキンを基質とする位置選択的なイソキノリン合成を実施した。また、ロジウム近傍にカルボキシル基を変異導入により配置することによって、触媒活性が向上することも見出しており、タンパク質反応場のチューニングの有効性も実証した。このような探索を迅速化するために、バイオハイブリッド部分を表面提示したホールセル触媒系の構築に取り組んだ。細胞表面との連結を円滑にするために、ロジウム錯体の配位子の最適化を検討して、種々のチオール系配位子を試した結果、ジチオリン酸配位子で空配位座を保護したロジウム錯体では、タンパク質ホストと連結後に金属塩添加により脱保護を伴い、ロジウム錯体を再活性化可能であることを見出した。このバイオハイブリッド触媒は、硝酸銀存在下においてオキシム及びアルキンの付加環化反応において触媒活性を示すことも明らかにした。
  • アシンメトリー配位圏を有するバレル型バイオハイブリッド触媒の開拓
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2017年04月 -2019年03月 
    代表者 : 小野田 晃
     
    本研究では、多彩な反応性を示す金属錯体触媒と、精緻な反応場を提供するバレル型タンパク質の融合により、アシンメトリー配位圏を有するバイオハイブリッド触媒を構築し、従来の金属錯体や酵素にはない新たな位置選択性や官能基選択性を付与した合成反応の開拓に取り組んだ。具体的には、反応性の高いRh錯体を固定化したバイオハイブリッド触媒を活用し、位置選択的な炭素-炭素結合形成反応、また、バレル空孔内に芳香環拡張型のアシンメトリー配位圏を構築し、不斉Diels-Alder 反応を実証した。タンパク質には、強固なベータバレル構造を有するニトロバインディンの疎水空孔を活用して、様々な金属錯体触媒を共有結合により残基選択的に固定化したバイオハイブリッド触媒を開発してきた成果を踏まえて、ペンタメチルシクロペンタジエニル配位子をもつRh(III)錯体を選択し、マレイミドを導入した錯体とニトロバインディンの疎水空孔内のシステインを共有結合的に連結可能な手法を確立した。ジチオリン酸配位子で空配位座を保護したRh(III)錯体をタンパク質に連結後、硝酸銀の添加により、Rh(III)錯体を活性化する手法である。このバイオハイブリッド触媒は、硝酸銀存在下、フェニルオキシム及びアルキンの付加環化反応において触媒活性を示すことを明らかにした。ニトロバインディンの疎水性空孔にグルタミン酸を導入することによって、触媒活性が向上することを見出しており、Rh(III)錯体近傍のアシンメトリー空間の構築を成功した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2015年07月 -2019年03月 
    代表者 : 小野田 晃, 林 高史, 氷見山 幹基, 立川 賢悟, 青木 亜由美
     
    本研究は、光エネルギーを利用して水を水素源に生成したFeヒドリドを活性種にもつFeバイオ触媒を開発した。マレイミド部を導入したジチオラート架橋Fe 二核錯体を、強固なバレル構造をもつニトロバインディンの疎水空孔内に共有結合を介して連結し、Feバイオハイブリッド触媒を構築した。鉄二核錯体のジチオラート架橋配位子をアザジチオラートに変換し、第二配位圏にプロトンシャトルとなるアミノ酸残基を適切な位置にグルタミン酸やリジンなどの残基を導入することによって、水素発生の活性向上を達成した。
  • 日本学術振興会:科学研究費助成事業 国際共同研究加速基金(国際共同研究強化)
    研究期間 : 2017年 -2019年 
    代表者 : 小野田 晃
     
    多彩な反応性をもつ金属錯体触媒と、精緻かつ多様な反応場を提供するタンパク質を融合したバイオハイブリッド触媒は、従来にはない位置選択性・官能基選択性・基質選択性の実現が期待される。本研究では、高機能なバイオハイブリッド触媒を効率的に創製するために、指向性進化工学の手法を取り入れた触媒探索法の開発に取り組んだ。夾雑な環境でロジウム錯体とタンパク質を連結する手法、またC-H結合官能基化により得られる生成物を蛍光法により迅速に検出する手法を開発し、ロジウム錯体をニトロバインディンタンパク質と連結したバイオハイブリッド触媒を指向性進化工学により高活性するためのホールセル技術プラットホームを確立した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 小野田 晃, 林 高史, 田中 雄大, 伊藤 実
     
    本研究では、燃料電池カソードでの酸素還元電極材料として、非貴金属活性点を組み込んだ含窒素カーボン電極触媒の開発を実施した。非貴金属原料に芳香環拡張型金属サレン錯体を活用する新手法により、触媒活性点の設計技術を高め、高活性・高耐久性を実現した非貴金属カーボン電極材料の調製と酸素還元反応における触媒活性評価を行った。鉄サレン錯体を含む原料を、バルカンX、ケッジャンブラック等のカーボン担体と混合した上で、焼成、酸洗浄により触媒を調製した。触媒活性の評価と同定の結果、芳香環を拡張したプリカーサーを使用した際に、効率的にFe-N活性点が形成され、4電子還元反応が効率的に進行していることを明らかとした。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 小野田 晃, 林 高史
     
    バクテリア細胞分裂において重要な役割を担うFtsZは、細胞膜上で集合化してリング状の構造体(Z-リング)を形成する。このFtsZはGTPの加水分解に伴い、集合構造の曲率を変化させながらZ-リングの収縮と細胞膜の分断を誘導する。このZ-リングが起点となりタンパク質群が集合化し、細胞分裂が進行する。これらの作用機序解明の点からも、FtsZの集合構造とその動的ダイナミクスは興味深い。本研究では、超分子的な相互作用を誘起するアダプタータンパク質を添加することでFtsZ集合体に外部から摂動を与え、その構造に変化を与える系を構築した。
  • 金属タンパク質と合成ポリマーから構成される機能性ハイブリッド界面の開発
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2015年04月 -2017年03月 
    代表者 : 小野田 晃
     
    本研究では、電子移動・触媒・センサー機能を有する金属タンパク質および金ナノ粒子や高分子などのナノ材料となる機能性元素ブロックを、生体分子に特有の精密な分子間相互作用を活用した機能性ハイブリッド界面を構築し、バイオマテリアル及び生体分子デバイスへの展開をめざした。金属タンパク質を階層化してハイブリッド化する技術を発展させて、合成ポリマーとの組み合わせにより、金属タンパク質の配向やメゾスコピック構造を制御したハイブリッド材料を創製に取り組んだ。特異な電子的・光学的性質をもつ金ナノ粒子は、多彩な機能性材料への応用が期待されている。直径10-100 nmの金ナノ粒子は、金の原子核に束縛された自由電子の集団振動周波数に相当する光を吸収し、表面プラズモン共鳴 (SPR)と呼ばれる光吸収特性を示すだけでなく、酸化チタンや酸化タングステンなどの半導体光触媒上に担持した際に、高い触媒活性を示す。半導体の光触媒活性は、担持金ナノ粒子の形状や、担体への担持構造が影響を及ぼすことから、今年度は、金ナノ粒子を含むハイブリッド材料の構築に取り組んだ。タンパク質などの生体分子間の超分子相互作用を利用した担持金ナノ粒子の形状制御を行い、生体分子-金界面形成により半導体光触媒の緻密な表面改質が可能であることを見出した。また、可視光応答性光触媒である 金ナノ粒子-WO3 複合体において、担持された金ナノ粒子の集合構造を自己集合性アミロイドペプチドにより制御し、その光電変換効率を評価した。アミロイドペプチドを修飾した金ナノ粒子は酸性条件下で繊維状の金ナノ粒子集合体を形成し、長波長域のプラズモン共鳴吸収を示すとともに WO3 の光電変換効率を向上に寄与することを明らかとした。
  • 金属タンパク質と金属ナノ粒子の階層化によるハイブリッド界面の構築
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2013年04月 -2016年03月 
    代表者 : 小野田 晃
     
    電子移動・触媒・センサー機能を有する金属タンパク質と多様な物性を持つ金属・半導体ナノ粒子のそれぞれを機能性の元素ブロックととらえ、生体分子の精密な分子間相互作用を活用して、金属タンパク質と金属ナノ粒子を階層化したハイブリッド型ナノ界面を電極基板上に構築した。安定性および量子収率に優れた半導体ナノ粒子を表面修飾することにより、ヘムタンパク質との複合化による触媒系を構築した。ヘムタンパク質としてミオグロビン(Mb)、半導体ナノ粒子としてCdTeナノ粒子(CdTe QD)を選択し、複合体の構築を行った。複合体におけるCdTe QDからMbへの電子移動反応および複合化後のヘムタンパク質機能について検証した。光還元によるMbの機能化について検証したところ、CO雰囲気下において可視光照射した際に、Fe(III)のmet-Mbは一電子還元を受けてFe(II)-CO錯体のCO-Mbに変換されることを明らかにした。ヘムタンパク質であるMbの機能を保持した状態でタンパク質への電子移動反応を高効率化したQD複合体の構築に成功しており、シクロデキストリンとアダマンタンの超分子相互作用を介して表面固定も有効であることを見出した。 電子移動の効率的なバイオ電極構築をめざし、電極上に固定した補酵素等の酸化還元中心に対しアポタンパク質を再構成することにより、酵素と電極間の効率的な電気伝導が可能となるバイオデバイスを作製した。具体的には、金ナノ粒子を固定化した電極表面にヘムを化学修飾し、その後アポタンパク質の再構成することによって、ヘムタンパク質を固定化修飾した電極を作製した。ヘム-ヘムポケット間の相互作用を活用した本系においてシトクロムb562の電子移動効率の優位性が明かとなった。
  • 日本学術振興会:科学研究費助成事業 若手研究(A)
    研究期間 : 2013年04月 -2016年03月 
    代表者 : 小野田 晃, 林 高史
     
    固体高分子型燃料電池は、高効率なエネルギー変換を実現する技術として最も期待されている。しかし、カソードでの酸素から水への4電子還元を伴う酸素還元反応の高活性な電極触媒の開発は以前として十分でない。本研究では、高効率に酸素還元反応を触媒している生体の金属酵素の多核金属中心を規範とし、非貴金属活性点を組み込んだ含窒素カーボン電極触媒の開発を実施した。非貴金属原料とした新たにヘム金属錯体や金属サレン錯体を活用し、触媒活性点のプリカーサ-を調製後に焼成する手法により、触媒活性点デザインの技術を高め、高活性・高耐久性を実現した非貴金属カーボン電極材料の調製と酸素還元反応における触媒活性評価を行った。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2010年04月 -2016年03月 
    代表者 : 林 高史, 小野田 晃
     
    生体内での生合成や代謝反応は、いわゆる直截的な有機合成反応の基本例である。その効率的な反応には生体触媒である酵素の関与が必須である。化学の立場で直截的反応を設計する際に、酵素を目的に応じて改変して利用することは、有効なアプローチの一つと言える。我々は、タンパク質の空孔に非天然の金属錯体を挿入することにより、天然の酵素では実現が難しい反応(C-H結合の活性化、C-C結合形成、水素発生等)の実施や反応の立体選択性の向上などに結びつくことを本課題研究で明らかにした。さらに、タンパク質空孔の反応場を遺伝子操作によってチューニングすることにより、反応の活性や選択性の更なる制御も可能となることを示した。
  • ヘムタンパク質を活用した異種タンパク質階層プログラミングとバイオデバイスへの展開
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2012年04月 -2015年03月 
    代表者 : 小野田 晃
     
    本研究は、電子移動・触媒・センサー機能を有するヘムタンパク質におけるヘム-ヘムポケットの相互作用を活用して、異種タンパク質の階層構造を電極基板上へプログラム構築するとともにバイオデバイスへの展開を目的として実施した。タンパク質の複雑な人工集合体やナノ構造体を精密構築しデバイス化するという観点から独創的な試みである。ヘムのプロピオン酸側鎖にマレイミドを導入し、シトクロムb562 (cyt b562) 表面に導入した一つのシステインとカップリングし、ヘムタンパク質自己集合体のモノマーユニットを調製した。タンパク質は、昨年度までと異なり、修飾位置を変更してユニットも調製をした。基板へのタンパク質の連結方向を180度変えたユニットについても調製を行った。さらに、プロトポルフィリンIX の中心金属を Zn に置換したユニットも調製した。金電極表面に自己組織化膜を形成後、ヘムあるいはZnプロトポルフィリンIX を縮合により表面修飾を行い、モノマーユニットを添加することにより、ヘムタンパク質集合体が階層的に集積化したバイオデバイスを作製した。タンパク質積層界面は、交流インピーダンス測定、水晶発振子マイクロバランス、原子間力顕微鏡により同定を行った。作製した一連の異種タンパク質階層化電極について、サイクリックボルタンメトリー及び微分パルスボルテンメトリーにより電気化学特性を明らかにした。犠牲試薬存在下でのキセノンランプ照射時の電流応答を評価し、Zn 置換のシトクロムを配向階層化した金電極は、カソード電流が検出されること、積層構造によって電流量が増大する現象を見出した。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2011年 -2012年 
    代表者 : 小野田 晃, 林 高史
     
    金属酵素は高い触媒活性と選択性を達成する極めて魅力的な金属反応中心をもつ。例えば、メタンの水酸化や窒素固定をはじめとする合成化学的に難易度の高い反応を常温常圧の温和な条件下で触媒することが可能である。本研究では、タンパク質マトリクスを活用し、非天然二核金属中心を有する生体触媒の構築を行った。第一配位圏の合理的な二核金属配位環境の再構築と、第二配位圏の設計を組み合わせた生体触媒を作製し、その構造および機能解析を行った。
  • ヘムタンパク質階層プログラミングによる機能性デバイスの創製
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2010年 -2011年 
    代表者 : 小野田 晃
     
    本研究では、電子移動・触媒・センサー機能を有するヘムタンパク質をターゲットとして、プログラム化されたヘムタンパク質階層構造を電極基板上へ構築し生体分子デバイスの創製をめざした。ヘムタンパク質超分子からなる集合体を活用して、ヘムタンパク質が基板表面に階層化したメゾスコピック界面の機能を明らかにした。ヘムタンパク質のヘム-タンパク質マトリクス相互作用により、自律凝集的に階層化したタンパク質集合構造を組み上げることが可能である。昨年度に引き続き、本年度は、この系に対して、光電変換の特性を組み込むために、亜鉛プロトポルフィリン (ZnPP) を含むタンパク質階層構造の構築を行った。電子伝達タンパク質シトクロムb562 の表面に ZnPPを結合したタンパク質をユニットとして亜鉛置換型のタンパク質集合体を調製した。一方で、ZnPP を金電極の表面の単分子膜状にアミド結合を介して修飾後に、タンパク質集合体を電極上にタンパク質とZnPP の相互作用を利用して固定化した。また、固定化するリンカーの長さを変えて、種々の電極修飾を行った。このタンパク質メゾスコピック界面の構造を詳細に調べると同時に、光電変換特性の検討を行った。まず、QCM、交流インピーダンス測定により、ZnPP修飾基板上にタンパク質オリゴマーを積層できていることを確認した。このタンパク質階層化電極の光照射時のカソード及びアノード電流を調べたところ、積層化によって光電流量が増大しており、タンパク質階層プログラミングにより電極界面特性の機能向上可能であることを見出した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2008年 -2010年 
    代表者 : 小野田 晃
     
    本研究では、タンパク質マトリクスを活用して多核金属中心を活性部位に導入することにより、新たな高機能生体触媒の創製に取り組んだ。酸素結合機能をもつ鉄二核タンパク質DcrH-Hrの機能解析結果を踏まえて、活性部位近傍のアミノ酸変異導入し、鉄二核中心の反応性の変換に成功した。また、水素発生触媒活性を有する鉄二核ヘキサカルボニル中心を導入したヒドロゲナーゼ活性を有する新規な金属タンパク質が創出に成功した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2006年 -2008年 
    代表者 : 山村 剛士, 小野田 晃, 坂本 良太
     
    金ナノパーティクルを2次元平面上に自在に配列することは、多くの研究者が挑戦している目標であるが、従来の配列法では小型のナノパーティクルを設計パターンどおりに配列させることが出来なかった。本研究はこの問題に対して、重金属捕捉蛋白質MTとDNA結合蛋白質ZFの人工融合蛋白質ZFMTを合成し、金クラスター(Au11)と化学量論的に結合させた後、DNAの高次構造体上に定位することにより、幾何模様を描かせることに成功した。
  • カルシウムセンサー機能を有する人工DNA結合タンパク質の精密構築
    日本学術振興会:科学研究費助成事業 若手研究(B)
    研究期間 : 2006年 -2007年 
    代表者 : 小野田 晃
     
    本研究では、生体内のCaシグナルと関連したタンパク質発現と細胞機能を解明するためのプローブ分子として、塩基配列認識部位を自在に設計でき、かつ、Caセンサー機能を有する人工転写因子の創製を目指して研究を行った。本年度は、Caセンサー型転写因子の基盤タンパク質の調整を行った。すでに申請者は、ジンクフィンガーZif268を参考に、2つのフィンガーユニットのC端にCa結合タンパク質であるトロポニンCのヘリックスーターンーヘリックスのターン部分以降のモチーフをカップリングした、フユージョンタンパク質FlF2-Tnが、Caイオン存在下では、DNAとの結合が低下することを明らかにした。分子モデリングの結果を踏まえ、Ca結合によってフレキシブルなループ部分の構造変化によってDNAとの立体障害を引き起こす機構のためと考え、このような構造変化による結合阻害が大きくなるような変異を導入したタンパク質の大腸菌での発現系の構築を行った。目的のタンパク質をコードするDNA断片を用意し、これをマルトース結合タンパク質とのフユージョンタンパク質として発現するようにプラスミドに導入した。形質転換後の大腸菌BL21の培養条件、誘導条件の最適化を行った。また、ライセートから可溶性画分を、アミロースレジン及びヘパリンセファロースによるアフィニティーカラムクロマトグラフィー、次いで、DEAEカラムによる陰イオンカラムクロマトグラフィーによる最終精製標品を得る精製段階を確立した。同様に、DNAの認識部位が異なる変異タンパク質についても大量発現及び精製を行った。
  • 有機無機複合光成膜の合成・アミノ酸型ポルフィリンオリゴマーの利用
    日本学術振興会:科学研究費助成事業 特定領域研究
    研究期間 : 2005年 -2006年 
    代表者 : 山村 剛士, 小野田 晃
     
    本計画は「緑色植物の光合成チタコイド膜を参考に、有機・無機複合型ナノ構造を構築すること」である。この課題に対して平成18年度は以下の成果を得た。 1)14〜17年度にかけて我々はシアノバクテリアの光捕集蛋白質を参考に新しい原理に基づくアンテナクロロフィルの開発をおこない、また、長い蛍光寿命を有するポルフィリンアレイの構築と色素アレイのスペクトル制限分子力学シミュレーションプログラムの開発を行なってきたが、本年度はその集大成として色素配向の分布構造を明らかにし、PSIとの比較をおこなった。また、この成果は今後クロロフィル型の高効率光エネルギー輸送系の構築をおこなう基礎になると期待できる。 2)ヒドロゲナーゼのモデル化に関する生物無機化学的研究を試み、[NiFe]活性中心に関して、システイン含有テトラペプチドを配位子とするニッケル塩の合成・構造解析(NMR、EXAFS)に成功し、[NiFe]ヒドロゲナーゼ中心構造構築のためのプラットフォームづくりをおこなった。この成果は今後Feを導入し、安定な光合成型光エネルギー変換水素発生系を構築するための基礎になるものと期待される。 3)クロロフィル誘導体を用いて、シアノバクテリアPSIIの光電変換中心であるいわゆるスペシャルペアの忠実構造モデルの合成に成功した。このモデルは今後アクセサリークロロフィルのモデルやフェオフィチンモデルを結合させた系への発展の基礎になるものと考えている。 4)上記アンテナクロロフィルモデルをシリコン型ベシクルの脂質2重膜中に高密度に閉じ込めることに成功した。この成果は、将来、初発電荷分離の反応中心、水素発生サイト、酸素発生サイトをシリコンナノベシクルの表面に組み込む基礎になるものと期待される。
  • 人工DNA結合タンパク質を利用したDNA情報ナノ空間における機能性錯体の精密配置
    日本学術振興会:科学研究費助成事業 特定領域研究
    研究期間 : 2005年 -2005年 
    代表者 : 小野田 晃
     
    本研究では、DNAにより構成される空間を、塩基配列情報を含んだ情報ナノ空間ととらえ、この情報に基づき金属錯体などの機能性物質群を分子レベルで精緻に配置することを目的をとして、金属錯体を結合した人工亜鉛フィンガーを合成及びジンクフィンガーによる金属錯体配列を行うテンプレートを拡張するために、2重鎖を束ねたDXモチーフの検討を行い、2次元、3次元上に定位する手法の確立を行った。DXには4または5本鎖からなる数種類があるが、本研究では5本鎖からなる逆平行型のDXを用いた。ZFとしてGGGGCGを認識する2ドメインのF1F2、および、トリスビピリジンRu(II)錯体を結合したRu-F1F2を用いた。X線構造解析により明らかにされたDNAのZF結合部位とZF本体の空間配置を考慮して、認識塩基配列のDX内での位置を設計した。ZFとDXとの結合及び相互作用についてはゲルシフトアッセイ(EMSA)を用いて調べた。EMSA実験でのDXは全て[γ-^<32>P] ATPで1つのssDNAを5'-末端標識後に、アニーリングしたものを用いた。認識部位を移動することで、ジンクフィンガー及びRu錯体の位置が位相をもって変化する。そこで、ZF結合部位の位相を変化させたDXテンプレートを用意し、ZFを導入したところ、すべての場合において結合することが分かった。ZF結合部位の位置を交叉部の右、左、あるいは両方に組み込んだ配列においても、ZFが結合可能であることが分かった。それぞれの位相についてZF部位を4ユニットに増加させたところ、ZF濃度を増加させるにつれて目的通りに複数のZFユニットを配置できることがわかった。本年度の研究成果により、DX分子をテンプレートに用いることによって、金属錯体間の距離を精密に制御して多数配列した系を構築できることを明らかにした。
  • DNA結合蛋白質を利用したナノドット・分子素子の自由配列と量子細線の形成
    日本学術振興会:科学研究費助成事業 萌芽研究
    研究期間 : 2004年 -2005年 
    代表者 : 山村 剛士, 小野田 晃
     
    本年度の成果は以下のとおりである。 1)光活性分子素子とジンクフィンガーの融合・DNAとの結合:まず、従来の配列を変えN端側にルテニウム(オスミウム)トリスバイピリジン錯体部を移した。 Tbp^-F1F2:Tbp^-GTGEKPYG-CRICGRNFSRSDDLTRHIRTHTGEKPYGCRICGRNFSRSDHLTR-HIRTHTGEKPYYG この配列換えによりケミカルライゲーション法の適用が可能になり、自由にフィンガー側の配列を選べるようになる。改めてTbp^-ZFの合成法を検討し、まず、ライゲーションの原料になるTbp^-GTGEKPYGチオエステルの大量合成法確立に努めた。その結果、TAMPAL resinから固相法により伸長し、直接チオエステルを切り出す方法が有効であることを見出した。この方法でTbp^-GTGEKPYG-F1F2とTbp^-GTGEKPYG-F2F1(F1、F2は何れも単鎖のジンクフィンガー)の合成を試み、前者については単離・精製に成功し、更に、50bp DNA上に5個直列配列させることに成功した。後者についても、Tbp^-GTGEKPYG-F2の合成に成功している。 2)ドットとの結合能を有する新規ジンクフィンガー融合蛋白質の合成:前年度における検討から、金のドットと1:1で反応し、安定にハンドリングすることが可能なペプチドとして、メタロチオネイン(MTIIのαドメイン)とジンクフィンガーの融合蛋白質の合成を企図した。 F3F3-MT : TGEKPYGCRICGRNFSRSDNLTRHIRTHTGFKPYGCRICGRNFSRSDNLTRHIRTHTGEKP YG-MTII_α 様々な検討の結果、固相合成後液相でのフラグメント縮合によりこの融合蛋白質の単離・生成に成功した。現在、金ドットの導入を検討中である。
  • 金属錯体・DNA複合超分子.二次元情報グリッドの創製
    日本学術振興会:科学研究費助成事業 若手研究(B)
    研究期間 : 2004年 -2005年 
    代表者 : 小野田 晃
     
    本研究では、DNAにより構成される2次元基盤及び、基盤の塩基配列情報を読み出す分子としての亜鉛フィンガータンパク質に金属錯体を結合したユニットにより、機能性物質群を分子レベルで精緻に配置することを目的をとして研究を行った。本研究の開始時点では、DNAの格子としてポルフィリン分子を使いグリッド化を検討したが、より効率的な手法としてDNAのみからなる2次元DNA基盤となるDXモチーフを使用した。また、機能部位の配列するユニットである2ユニットの亜鉛フィンガーと金属錯体を結合したユニットの合成を行った。ZFとしてGGGGCGを認識する2ドメインのF1F2、および、トリスビピリジンRu(II)及び、Os(II)錯体を結合したフィンガーの合成に成功した。基盤のDXには4または5本鎖からなる数種類があるが、本研究では5本鎖からなる逆平行型のDXを用いた。X線構造解析により明らかにされたDNAのZF結合部位とZF本体の空間配置を考慮して、認識塩基配列のDX内での位置を設計した。ZFとDXとの結合及び相互作用についてはゲルシフトアッセイ(EMSA)を用いて調べた。EMSA実験でのDXは全て[γ-^<32>P]ATPで1つのssDNAを5' -末端標識後に、アニーリングしたものを用いた。認識部位の位相、位置、数を変えた様々なテンプレートを用いてスクリーニングを行い、DX分子をテンプレートに用いることによって、金属錯体間の距離を精密に制御して多数配列した系を構築できることを明らかにした。また、ジンクフィンガーによる機能部位配列と組み合わすことができる新しいDNA基盤分子として、リンカーを介して金属ポルフィリンを結合した2重鎖DNAの合成にも成功した。
  • 電極・界面上への光合成エネルギー変換モデル構築.ポルフィリンアミノ酸含有ペプチド
    日本学術振興会:科学研究費助成事業 特定領域研究
    研究期間 : 2003年 -2004年 
    代表者 : 山村 剛士, 小野田 晃
     
    本研究は、シアノバクテリアの反応中心を参考にして、最終的に水の可視光分解を実現すること目指しており、その第一段階として、ポルフィリンを用いたシアノバクテリア型アンテナクロロフィルモデルの構築を目指した。シアノバクテリアのアンテナクロロフィルは、隣接クロロフィル同士が6〜26Å離れて様々に配向・集合している)。そのモデル化のため短いリンカー部を有するポルフィリンアミノ酸のオリゴマー(二、四、八量体)の合成を行った。 オリゴマー中のポルフィリンの配向は、励起子バンドの形成と分光挙動に大きな影響を与えるため、スペクトルデータからオリゴマー中のポルフィリン配向をシミュレートすることが可能である。我々はこのための解析プログラムを開発した。また、オリゴマーの蛍光収率を2座配位子により制御し、蛍光を著しく増大させる条件を明らかにした。上記プログラムを用いた配向解析の結果、我々のオリゴマーはアンテナクロロフィルとよく似た形態を持ち、エチレンジアミンの添加にポルフィリン同士の会合はface-to-face型からhead-to-tail型に変化する。この構造変化に伴うエネルギーダイヤグラムの変化と、隣接ポルフィリン間におけるエネルギー移動の速度を計算した結果、B-band部を通してのエネルギー移動速度はアンテナクロロフィルに匹敵するが、Q-band部分は、それ程の効率にはならない。
  • 光応答を用いたペプチド機構及びNH・・・O水素結合の変換による鉄錯体の反応性制御
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    研究期間 : 2002年 -2004年 
    代表者 : 小野田 晃
     
    鉄含有金属酵素においては、鉄イオンの高い反応性は、基質と結合したとき等の特定の場合にのみ有効となり、通常は不活性化させた状態にある。このような生体での巧妙な機構を解明するために、本申請者は、現在までの研究成果からで明らかになった配位酸素原子へのNH…O水素結合の機能を光制御系の構築を進めている。これまでに、すでに、NH…O水素結合の機能として、金属-酸素結合を安定化すること、また、金属原子の状態を変化することを明らかにしている。そこで、特に、天然の鉄酵素にも多く見られるカルボキシラート配位への水素結合を光制御する配位子、3-(3-t-BuCONHC_6H_4CH=N)C_6H_4COOHを設計し合成を行った。申請者が明らかにした、NH…O水素結合がカルボキシレートアニオン状態のみで形成されることを踏まえて、光照射によるアゾメチン基のシス・トランスの変換挙動等の性質について検討している段階である。 水素結合を形成した鉄錯体の合成についても検討を行っており、まず、アミド基の回転が制限されているカルボン酸配位子を用いて錯体の単離し、構造等の詳細な情報を調べている。現在、水素結合の強度により配位原子の塩基性を変えることにより鉄中心の配位構造を変化できることが明らかになってきた。カルボキシル基とアミド基をケンプ酸でつなげた新規配位子についても合成を行い、プロトン化に連動した構造変化も見いだすことができた。
  • 配位酸素原子へのNH・・・O水素結合による金属一酸素結合性及びペプチド構造制御
    日本学術振興会:科学研究費助成事業 特別研究員奨励費
    研究期間 : 1999年 -2001年 
    代表者 : 小野田 晃
  • Mononuclear and Polynuclear ca-phosphate complex with Bulky Amide Ligand
  • Function of NH…O hydrogen bonds to coordinated oxygen atom cooperating with peptide comformation
  • 非天然金属中心を有する人工生体触媒の創製

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