| Co-Investigator(Kenkyū-buntansha) |
YAMAGUCHI Hiroko Kumamoto University, Graduate School of Science and Technology, Research Associa, 大学院・自然科学研究科, 助手 (60040424)
NISHIYAMA Katsuhiko Kumamoto University, Faculty of Engineering, Assistant Professor, 工学部, 講師 (10202243)
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| Research Abstract |
In the present study, surface functions of modified electrodes for electron transfer reactions of metalloproteins have been examined by using gold single crystal electrode surfaces.
1. Preparation and characterization of single crystal electrode surfaces :
Gold single cryatal surfaces were prepared by both vacuum evaporation and flame-annealing-quenching methods, and their surfaces were characterized by STM/AFM and electrochemical measurements as a function of preparation conditions.
2. Functional electrode surfaces for electron transfer reactions of metalloproteins :
(1) Surface structures of modified Au single crystal electrodes for cytochrome c electrochemistry were studied by STM, surface-enhanced IR absorption spectroscopy (SEIRAS) and the electrochemical reductive desorption technique. On the Au(1 11) surface, for example, adsorbed 4-pyridinethiol (4-PySH) showed the rectangular unit cell of p(5*<square root>3R-3Oﾟ) structure with an interaction of two neighboring 4-PySH, while the 2
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-PySH modified electrode showed a p(4*<square root>7R-4O.9ﾟ) structure with no dimer formation, suggesting that 2-PySH adsorbs at both thiolate S and pyridine N atoms.
(2) Using highly hydrophilic sin-face of In203 electrodes, biological functions and electron transfer kinetics of native and reconstituted myoglobins were found to be related very much to the heme structure, such as the porphyrin backbone of the heme, type of metal ion of the redox center, coordination structure etc.
3. Modification with thiols on single crystal gold electrode surfaces :
A very small amount (ca. 1%) of sulfide impurity in a thiol modifier solution was found to make the modified surface structure complicated in some cases. However, the structure of modified surface was very much controlled by thermodynamic and kinetic aspects of the modification processes. The reductive desorption peak potentials of thiols adsorbed on the electrode surfaces were found to be used as an excellent measure for predicting the structures of the modified surfaces. Electrochemical fabrication for the thiol modified surface has also developed. Less
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