Proteins, electron transmission, direct

The electrochemistry of redox proteins is characterized by a strong dependence on the nature of the electrode surface. Extensive studies by Hill etal. (cited in Refs. 31-33) show that provided the electrode surface is modified to be compatible with the redox protein, direct electrochemistry can be rapid. Their studies have emphasized the importance of the orientation of the protein at the electrode surface so that the distance over which the electron must transfer is not excessive. This is important because redox sites in these proteins are generally located toward one side of the protein, and the exponential dependence of the electron transmission coefficient/ei on distance means that the rate of electron transfer drops rapidly as distance increases (Fig. 9.11). Most of this work has used low molecular weight modifiers adsorbed at the electrode surface, " although similar effects should be possible at polymer-modified electrode surfaces. 

Direct transmission of electrons through the rc-systems of proteins or nucleic acids now seems a rather unlikely possibility in living systems. Propagation of electronic excitation in biopolymers will be considered in another chapter of this volume. Recalling the phenomenon of biolumines-... 

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