2002 Fiscal Year Annual Research Report

補酵素類縁体の電子移動反応制御とその応用

Research Project

Project/Area Number	01J00471
Research Institution	Osaka University
Principal Investigator	大久保敬大阪大学, 大学院・工学研究科, 特別研究員(PD)
Keywords	電子移動反応 / 酸素化反応 / ニコチンアデニンジヌクレオチド / アクリジニウム / アルキルベンゼン / オレフィン / アルデヒド / 光誘起電子移動
Research Abstract	本研究では生体内における電子伝達の中心的役割を果たしている補酵素類縁体の中で、ニコチンアデニンジヌクレオチド(NAD)類縁体に着目し、その電子移動特性を明らかにするために系統的な研究を行い以下のような結果を得た。 NAD^+類縁体の非常に高い光酸化力を利用することにより、種々のアルキルベンゼン類やオレフィン類等を光電子移動酸化できることがわかった。このことを用いて分子状酸素によるα-メチルスチレンおよびアルキルベンゼン類の選択的酸素化反応が可能になることを見い出した。α-メチルスチレンおよび10-メチルアクリジニウムイオン(AcrH^+)を含む酸素飽和アセトニトリル溶液に水銀ランプで300nm以上の波長の光を照射すると、アセトフェノンが主生成物として得られた。反応の限界量子収率はほぼ100%に近い値が得られ、本反応は連鎖反応を経由しない酸素化反応であることを見いだした。反応機構は、レーザーフラッシュフォトリシスによるラジカルイオン種の検出、蛍光消光、量子収率の解析から確かめることができた。次にp-キシレンを用いた場合も、9-置換10-メチルアクリジニウムイオン(AcrR^+,R=H, Ph)を光触媒として酸素分子による酸素化が光電子移動反応を経て効率良く進行することがわかった。基質として電子吸引性の置換基を有するアルキルベンゼン(例えばp-トルニトリル)では、AcrR^+の一重項励起状態への電子移動が起こらないので、酸素化反応も進行しない。しかし、光触媒としてより酸化力の強い光増感剤を用いると、p-トルニトリルの酸素化反応が進行するようになった。一方、基質として電子供与基を有する置換基を有するアルキルベンゼン類を用いた場合は、最初の酸素化生成物からもAcrR^+の一重項励起状態への電子移動が起こるので、さらに酸素化反応が進行した。このように光電子移動を利用して基質の酸素化を行なう場合は、適切な酸化力を有する光増感剤を使用することにより、基質の選択的酸素化反応が可能になることがわかった。

Research Products
(21 results)

All Other

All Publications (21 results)

[Publications] Kei Ohkubo et al.: "Evidence that gold(III) porphyrins are NOT electrochemically inert : facile generation of gold(II) 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin"Chemical Communications. 356-357 (2002)
[Publications] Kei Ohkubo et al.: "DNA Cleavage via Superoxide Anion Formed in Photoinduced Electron Transfer from NADH to γ-Cyclodextrin-Bicapped C60 in an Oxygen-Saturated Aqueous Solution"The Journal of Physical Chemistry B. 106. 2372-2380 (2002)
[Publications] Kei Ohkubo et al.: "Formation of Superoxide-Metal Ion Complexes and the Electron Transfer Catalysis"Coordination Chemistry Reviews. 226. 71-80 (2002)
[Publications] Kei Ohkubo et al.: "Photophysical and Electrochemical Properties of New Bacteriochlorins and Characterization of Radical Cation and Radical Anion Species"The Journal of Physical Chemistry A. 106. 5105-5113 (2002)
[Publications] Kei Ohkubo et al.: "Effects of magnesium ion on kinetic stability and spin distribution of phenoxyl radical derived from a vitamin E analogue : mechanistic insight into antioxidative hydrogen-transfer reaction of vitamin E"Journal of Chemical Society, Perkin, Transaction 2. 1520-1524 (2002)
[Publications] Kei Ohkubo et al.: "Electron Transfer Reduction of a Highly Electron-Deficient Fullerene, C_<60>F_<18>"Chemical Communications. 1952-1953 (2002)
[Publications] Kei Ohkubo et al.: "Fluorescence Maxima of 10-Methylacridone-Metal Ion Salt Complexes : A Convenient and Quantitative Measure of Lewis Acidity of Metal Ion Salts"Journal of the American Chemical Society. 124. 10270-10271 (2002)
[Publications] Kei Ohkubo et al.: "Direct Detection of Superoxide Anion Generated in C60-Photosensitized Oxidation of NADH and an Analogue by Molecular Oxygen"Journal of Chemical Society, Perkin, Transaction 2. 1833 (2002)
[Publications] Kei Ohkubo et al.: "Small Reorganization Energy of Intramolecular Electron Transfer in Fullerene-Based Dyads with Short Linkage"The Journal of Physical Chemistry A. 106. 10991-10998 (2002)
[Publications] Kei Ohkubo et al.: "Effects of Metal Ions Distinguishing Between One-Step Hydrogen-and Electron-Transfer Mechanisms for the Radical-Scavenging Reaction of (+)-Catechin"The Journal of Physical Chemistry A. 106. 11123-11126 (2002)
[Publications] Kei Ohkubo et al.: "A key role for old yellow enzyme in the metabolism of drugs by Trypanosoma cruzi"The Journal of Experimental Medicine. 196. 1241-1251 (2002)
[Publications] Kei Ohkubo et al.: "Metal Ion-Catalyzed Diels-Alder and Hydride Transfer Reactions. Catalysis of Metal Ions in the Electron Transfer Step"Journal of the American Chemical Society. 124. 14147-14155 (2002)
[Publications] Kei Ohkubo et al.: "Electron-Transfer Mechanism in Radical-Scavenging Reactions of Flavonoids"Free Radical of Biological Medicine. 33. S308-S309 (2002)
[Publications] Kei Ohkubo et al.: "A Planar Catechin Analogue as a Promising Antioxidant with Reduced Prooxidant Activity"Chemical Research in Toxicology. 16. 81-86 (2003)
[Publications] Kei Ohkubo et al.: "Driving Force Dependence of Intermolecular Electron Transfer Reactions of Fullerenes"Chemistry -A European Journal. 9(印刷中). (2003)
[Publications] Kei Ohkubo et al.: "Electron Transfer Properties of Bisphenol Derivatives in Relation with the Developing Properties In Silver Salt Photothermographic Systems"Journal of the Imaging Science Technology. (印刷中). (2003)
[Publications] Kei Ohkubo et al.: "Electrodes Modified with meso, meso-Linked Porphyrin Oligomers"Nano Letters. 3(印刷中). (2003)
[Publications] Kei Ohkubo et al.: "Quantitative Evaluation of Lewis Acidity of Metal Ions with Different Ligands and Counter Ions in Relation with the Promoting Effects of Lewis Acids on Electron Transfer Reduction of Oxygen"The Journal of Organic Chemistry. 68(印刷中). (2003)
[Publications] Kei Ohkubo et al.: "Remarkable Effects of Counter Ions on Scandium Ion-Promoted Electron Transfer Reactions"Chemical Communications. (印刷中). (2003)
[Publications] Kei Ohkubo et al.: "Fullerenes : The Exciting World of Nanocages and Nanotubes, Kamat, P. V. ; Guldi, D. M. ; Kadish, K. M. Eds. ; The Electrochemical Society, Inc. : Pennington, NJ"Unequivocal Observation of the Marcus Inverted Region for Intermolecular Electron. Transfer Oxidation of Fullerenes. 12 (2002)
[Publications] Kei Ohkubo et al.: "Fullerenes : The Exciting World of Nanocages and Nanotubes, Kamat, P. V. ; Guldi, D. M. ; Kadish, K. M. Eds. ; The Electrochemical Society, Inc. : Pennington, NJ"Intramolecular Electron Transfer in Bacteriochlorin-C_<60> and Zinc Chlorin-C_<60> Dyads. 12 (2002)

2002 Fiscal Year Annual Research Report

補酵素類縁体の電子移動反応制御とその応用

Principal Investigator

大久保 敬 大阪大学, 大学院・工学研究科, 特別研究員(PD)

Research Products

[Publications] Kei Ohkubo et al.: "Evidence that gold(III) porphyrins are NOT electrochemically inert : facile generation of gold(II) 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin"Chemical Communications. 356-357 (2002)

[Publications] Kei Ohkubo et al.: "DNA Cleavage via Superoxide Anion Formed in Photoinduced Electron Transfer from NADH to γ-Cyclodextrin-Bicapped C60 in an Oxygen-Saturated Aqueous Solution"The Journal of Physical Chemistry B. 106. 2372-2380 (2002)

[Publications] Kei Ohkubo et al.: "Formation of Superoxide-Metal Ion Complexes and the Electron Transfer Catalysis"Coordination Chemistry Reviews. 226. 71-80 (2002)

[Publications] Kei Ohkubo et al.: "Photophysical and Electrochemical Properties of New Bacteriochlorins and Characterization of Radical Cation and Radical Anion Species"The Journal of Physical Chemistry A. 106. 5105-5113 (2002)

[Publications] Kei Ohkubo et al.: "Electron Transfer Reduction of a Highly Electron-Deficient Fullerene, C_<60>F_<18>"Chemical Communications. 1952-1953 (2002)

[Publications] Kei Ohkubo et al.: "Fluorescence Maxima of 10-Methylacridone-Metal Ion Salt Complexes : A Convenient and Quantitative Measure of Lewis Acidity of Metal Ion Salts"Journal of the American Chemical Society. 124. 10270-10271 (2002)

[Publications] Kei Ohkubo et al.: "Direct Detection of Superoxide Anion Generated in C60-Photosensitized Oxidation of NADH and an Analogue by Molecular Oxygen"Journal of Chemical Society, Perkin, Transaction 2. 1833 (2002)

[Publications] Kei Ohkubo et al.: "Small Reorganization Energy of Intramolecular Electron Transfer in Fullerene-Based Dyads with Short Linkage"The Journal of Physical Chemistry A. 106. 10991-10998 (2002)

[Publications] Kei Ohkubo et al.: "Effects of Metal Ions Distinguishing Between One-Step Hydrogen-and Electron-Transfer Mechanisms for the Radical-Scavenging Reaction of (+)-Catechin"The Journal of Physical Chemistry A. 106. 11123-11126 (2002)

[Publications] Kei Ohkubo et al.: "A key role for old yellow enzyme in the metabolism of drugs by Trypanosoma cruzi"The Journal of Experimental Medicine. 196. 1241-1251 (2002)

[Publications] Kei Ohkubo et al.: "Metal Ion-Catalyzed Diels-Alder and Hydride Transfer Reactions. Catalysis of Metal Ions in the Electron Transfer Step"Journal of the American Chemical Society. 124. 14147-14155 (2002)

[Publications] Kei Ohkubo et al.: "Electron-Transfer Mechanism in Radical-Scavenging Reactions of Flavonoids"Free Radical of Biological Medicine. 33. S308-S309 (2002)

[Publications] Kei Ohkubo et al.: "A Planar Catechin Analogue as a Promising Antioxidant with Reduced Prooxidant Activity"Chemical Research in Toxicology. 16. 81-86 (2003)

[Publications] Kei Ohkubo et al.: "Driving Force Dependence of Intermolecular Electron Transfer Reactions of Fullerenes"Chemistry -A European Journal. 9(印刷中). (2003)

[Publications] Kei Ohkubo et al.: "Electron Transfer Properties of Bisphenol Derivatives in Relation with the Developing Properties In Silver Salt Photothermographic Systems"Journal of the Imaging Science Technology. (印刷中). (2003)

[Publications] Kei Ohkubo et al.: "Electrodes Modified with meso, meso-Linked Porphyrin Oligomers"Nano Letters. 3(印刷中). (2003)

[Publications] Kei Ohkubo et al.: "Quantitative Evaluation of Lewis Acidity of Metal Ions with Different Ligands and Counter Ions in Relation with the Promoting Effects of Lewis Acids on Electron Transfer Reduction of Oxygen"The Journal of Organic Chemistry. 68(印刷中). (2003)

[Publications] Kei Ohkubo et al.: "Remarkable Effects of Counter Ions on Scandium Ion-Promoted Electron Transfer Reactions"Chemical Communications. (印刷中). (2003)

[Publications] Kei Ohkubo et al.: "Fullerenes : The Exciting World of Nanocages and Nanotubes, Kamat, P. V. ; Guldi, D. M. ; Kadish, K. M. Eds. ; The Electrochemical Society, Inc. : Pennington, NJ"Intramolecular Electron Transfer in Bacteriochlorin-C_<60> and Zinc Chlorin-C_<60> Dyads. 12 (2002)

大久保敬大阪大学, 大学院・工学研究科, 特別研究員(PD)