The photoactivation of E. coli Photolyase involves, after photoexcitation of the chromophor and energy transfer to FAD, a long range hole transfer along a chain of Trp residues. Since this process  could not be modeled using Marcus theory with parameters computed with classical equilibrium MD simulations, we used fully coupled nonadiabatic (Ehrenfest) quantum mechanics/molecular mechanics (QM/MM) simulations. Due to the large system size which has to be treated quantum mechanically, we have developed a coarse-grained quantum/classical methodology, which allows to describe the dynamics of the electronic system coupled to the dynamics of the protein in water solvent. Charge transfer rates are in excellent agreement with experimental data and the simulations provide a more detailed picture of electron transfer than a classical analysis of Marcus parameters. The protein and solvent both strongly in?uence the localization and transport properties of a positive charge, but the directionality of the process is mainly caused by solvent polarization. The time scales of charge movement, delocalization, protein relaxation and solvent reorganization overlap and lead to nonequilibrium reaction conditions.

Modeling fast photo-activated electron transfer in E. coli photolyase

244th National Meeting (2012)

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