Coherent Electron Transfer in Cytochrome Nanowires at 300 K

Abstract

Electron transfer in cytochrome OmcZ and OmcS “nanowires” is explored computationally by integrating the quantum-mechanical stochastic Liouville equation with fluctuating energies and interaction matrix elements obtained from molecular-dynamics simulations and including a detailed treatment of vibronic coupling. Electron density oscillates between adjacent hemes very rapidly relative to thermal equilibration. These oscillations last for about 1.5 ns, which is long enough for a coherent wave of electron density to travel ∼60 Å, more than the length of the proteins’ subunits. The calculated rates of electron flow underestimate the measured rates but reproduce the finding that long-range diffusion of electrons is significantly faster in OmcZ than in OmcS.