In the following, we limit our consideration to molecular structures of the RCs from PSII, PSI, and bacteria characteristical to the Thermococcus vulcanus, Synechococcus elongatus, and Rhodobacter sphaeroides photosynthetic organisms, respectively. The corresponding crystal structures were taken from Protein Data Bank (PDB) entries 3WU2 , 1JB0 , and 1M3X . Similar RCs found in other organisms as well as mutants of the ones mentioned above are outside the scope of this paper and are not discussed here.