Effect of hydrogen bonds on the energetics of electron transfer

For a model system consisting of a special pair of bacteriochlorophyll molecules (P) and a primary quinone with the nearest environment (QA) (which are acceptor and donor in the recombination reaction in Rhodobacter sphaeroides reaction center, respectively), energies of P(+)Q(A)(-) and PQ(A) states were calculated. Calculations were performed using several stable QA conformations differing by the positions of hydrogen bond protons. Essential influence of proton positions on the energy of vertical transition P(+)Q(A)(-) -> PQ(A) was shown.