Electrical communication between horse heart cytochrome c and electrodes in the presence of DNA or RNA

Abstract

Electrical communication between electrodes and enzymes has received active interest from the viewpoints of the clarification of electron transport mechanisms in biological systems, and of applications to biochemical sensors and biocatalyst electrodes. As has been reviewed by Armstrong et al. [l], direct electron exchange between electrodes and cytochrome c, one of the electron transport enzymes in mitochondria, has been successfully investigated by using metal oxide electrodes like In,O, [2], and promotors such as 4,4’-bipyridyl [3], dithiobis(ethanoic acid) [4], and bis(4-pyridyl)disulfide [5]. A feature common to the above promotors is that electron-rich nitrogen atoms or anions, which are able to interact with positively charged lysine residues in cytochrome c, are present at several tenths of a nm apart from electrode surfaces at the adsorbed state. We chose DNA or RNA and studied their suitability as a promotor, because they have negative charges and are actually present in mitochondria. As a result, we discovered that DNA or RNA works as an effective promotor by interacting electrostatically with the positively charged patch of cytochrome c.