Electrochemistry of Protein Electron Transfer

Abstract

Protein fold and slow relaxation times impose constraints on configurations sampled by the protein. Incomplete sampling leads to the violation of fluctuation-dissipation relations underlying the traditional theories of electron transfer. The effective reorganization energy of electron transfer is strongly reduced thus leading to lower barriers and faster rates (catalytic effect). Electrochemical kinetic measurements support low activation barriers for protein electron transfer. The distance dependence of the rate constant displays a crossover from a plateau at short distances to a long-distance exponential decay. The transition between these two regimes is controlled by the protein dynamics.