The influence of electrostatic interactions and intramolecular dynamics on electron transfer from the cytochrome subunit to the cation ?radical of the bacteriochlorophyll dimer in reaction centers from Rps. viridis

Coupling of Electron Transfer and Protein Dynamics

“…The values of the parameters seem to be reasonable. Thus, we conclude that phenomenologically treating the effects of dynamical ligand modes and inelastic ET processes allows us to explain the temperature dependence of the ET reaction in a wide region from room temperature down to 50 K. Currently the effect of molecular dynamics on the electron transfer in proteins has been studied for individual cases [34,[40][41][42][43][48][49][50][51][52][53]. From the above it is concluded that protein dynamics has its own singularities and may be as important in the ET reactions as the spatial protein structure.…”

“…In [34] a shift of the temperature curves of the ET efficiency between css9-haem of tetrahaem cytochrome and primary donor p+ in reaction centres of Rhodopseudomonas viridis under a change in the oxidation state of haems CSS6 and CSS2 (Fig. 6) was attributed to a change in the reaction free energy due to electrostatic interaction of the electron being transferred with additional electrons which appear on haemes CSS6 and CSS2 upon their reduction.…”

Analysis of Kinetics of Electron Transfer in the Reaction Centers of Photosynthetic Bacteria Using the Rips—Jortner Model

“…It was established that the kinetics of the electron transfer is not exponential, and the character of kinetic curves varies with temperature and the degree of reduction of adjacent hemes in the cytochrome. The authors of [4] explained the changes in kinetic curves by a combined action of two factors-the molecular dynamics of the protein globule and a change in the electron energy level in heme c 380 due to…”

“…It was assumed for the second (heme c 310 is also reduced) or third stage of reduction (hemes c 310 and c 20 are reduced) that ∆ G i = ∆ G 1 + δ i and H i = H 1 -δ i , where ∆ G 1 and H 1 are the free energy of the reaction and the height of the tunneling barrier, respectively, for the first stage of reduction and δ i is the energy of electrostatic interaction ( i = 2, 3). However, despite an important role of protein molecular dynamics in the reaction of electron transfer, the authors of [4] analyzed the constants observed within the framework of a nonadiabatic approximation, according to which the rate of relaxation processes in the matrix does not influence the kinetics of transfer. Using such approach and assuming that ∆ G 3 = λ , the authors of [4] found that ∆ G 1 = 0.14 eV, ∆ G 2 = 0.18 eV, ∆ G 3 = 0.29 eV, and λ = 0.29 eV.…”

“…However, despite an important role of protein molecular dynamics in the reaction of electron transfer, the authors of [4] analyzed the constants observed within the framework of a nonadiabatic approximation, according to which the rate of relaxation processes in the matrix does not influence the kinetics of transfer. Using such approach and assuming that ∆ G 3 = λ , the authors of [4] found that ∆ G 1 = 0.14 eV, ∆ G 2 = 0.18 eV, ∆ G 3 = 0.29 eV, and λ = 0.29 eV. In this case, according to Eq.…”