Effect of protein relaxation on electron transfer from the cytochrome subunit to the bacteriochlorophyll dimer in Rps. sulfoviridis reaction centers within mixed adiabatic/nonadiabatic model

The broad set of nonexponential electron transfer (ET) kinetics in reaction centers (RC) from Rhodopseudomonas sulfoviridis in temperature range 297–40 K are described within a mixed adiabatic/nonadiabatic model. The key point of the model is the combination of Sumi–Marcus and Rips–Jortner approaches which can be represented by the separate contributions of temperature-independent vibrational (v) and temperature-dependent diffusive (d) coordinates to the preexponential factor, to the free energy of reaction ΔG=ΔGv+ΔGd(T) and to the reorganization energy λ=λv+λd(T). The broad distribution of protein dielectric relaxation times along the diffusive coordinate is considered within the Davidson–Cole formalism.