STUDY OF REACTION CENTER FUNCTION BY ANALYSIS OF THE EFFECTS OF SITE-SPECIFIC AND COMPENSATORY MUTATIONS

The protein portion of the reaction center (RC) complex is composed of three subunits: the intermembrane L and M chains, and the cytoplasmic H polypeptide. The cofactors are within the transmembrane region; they are related by approximate twofold symmetry as are the homologous L and M chains [1–4]. The cofactors consist of a bacteriochlorophyll dimer that is the primary electron donor, two bacteriochlorophyll monomers, two bacteriopheophytins, a non-heme iron atom, and two quinones which serve as the final electron acceptors.