Molecular Orbital Study of Electronic Asymmetry in Primary Donors of Bacterial Reaction Centers

Recent Electron-Nuclear-Double and -Triple Magnetic Resonance measurements on single crystals of reaction centers (RC’s) of the bacterium Rb. sphaeroides R-26 have revealed an asymmetric spin density distribution of the primary donor radical cation P 865 + 1. The observed ratio of spin densities, ρ L/ρ M, on the monomeric halves DL and DM of this dimer is approximately 2 : 1. A similar result had been found earlier for the primary donor radical cation P 960 +. in RC’s of Rps. viridis in liquid solution 2,3.