Theoretical analysis of the electronic asymmetry of the special pair in the photosynthetic reaction center: Effect of structural asymmetry and protein environment

We have studied the effect of structural differences and protein environment on electronic asymmetry of the special pair (SP) and the special pair cation radical in the bacterial photosynthetic reaction center with density functional theory. The electronic asymmetry has been found to derive from the difference in the orientation of methyl ester groups of SP halves. Due to the protein polarity enhancement with polarizable continuum model and point charge model, one electron oxidation is more significantly biased to the L-side bacteriochlorophyll a (SPL) in the both models.