Interprotein Electron Transfer: An Electrochemical Approach

• Published in: Denki kagaku oyobi kōgyō butsuri kagaku 2002/02/05, Vol.70(2), pp.82-90
• Main Author: NIKI, Katsumi
• Format: Article
• Language: English
• Subjects: Cytochrome c; Electron Tunneling; Gated Electron Transfer; Mutant; Organic Monolayers; Spectroelectrochemistry
• ISSN: 1344-3542; 2186-2451
• DOI: 10.5796/electrochemistry.70.82

Theoretical and experimental aspects of intermolecular and intramolecular electron-transfer kinetics of Ru-modified proteins and metal substituted cytochrome c are briefly discussed in the first part. In the second part, spectroelectro-chemical (electroreflectance) studies of horse heart cytochrome c electrostatically immobilized on carboxylic acid-terminated alkanethiol self-assembled monolayers on a well-defined gold electrode are discussed. It was found that intermolecular electron-transfer between cytochrome c and the carboxylic acid terminus is dynamically gated by configurational changes in the cytochrome c at the surface of alkanethiol self-assembled monolayers: transformation from the thermodynamically stable configuration to the electron-transfer complex, which features an efficient electron transfer channel, ultimately limits the rate of electron transfer. Kinetic measurements were carried out on horse heart cytochrome c and a recombinant rat cytochrome c (RC9-K13A), in which lysine 13 was replaced by alanine. The results revealed that the association of lysine 13 with the carboxylic acid terminus forms the electron transfer channel. A potential application of electrochemical techniques to mechanistic studies of biological intra- and intermolecular electron transfer processes is discussed as a concluding remark.