The Role of Protein Fluctuation Correlations in Electron Transfer in Photosynthetic Complexes

TL;DR

This paper investigates how the correlation properties of protein environment fluctuations influence electron transfer rates in photosynthetic complexes, providing exact equations and analyzing the effects of correlated versus uncorrelated fluctuations.

Contribution

It derives an exact system of differential equations for electron transfer dynamics considering correlated and uncorrelated protein fluctuations, offering analytic expressions for transfer rates.

Findings

Uncorrelated fluctuations can increase or decrease transfer rates.

Derived exact equations for average density matrix elements.

Compared effects of correlated and uncorrelated fluctuations.

Abstract

We consider the dependence of the electron transfer in photosynthetic complexes on correlation properties of random fluctuations of the protein environment. The electron subsystem is modeled by a finite network of connected electron (exciton) sites. The fluctuations of the protein environment are modeled by random telegraph processes, which act either collectively (correlated) or independently (uncorrelated) on the electron sites. We derived an exact closed system of first-order linear differential equations with constant coefficients, for the average density matrix elements and for their first moments. Under some conditions, we obtain analytic expressions for the electron transfer rates. We compare the correlated and uncorrelated regimes, and demonstrated numerically that the uncorrelated fluctuations of the protein environment can, under some conditions, either increase or decrease the electron transfer rates.