Isolated photochemical reaction centers from bacteriochlorophyll b - containing organisms

Optical, ESR and pulsed laser spectroscopic examination of isolated bacteriochlorophyll (BChl) b-containing reaction centers (RCs) demonstrates that their composition (1 P960 : 2 bacteriopheophytin (BPh) b : 2 cyt c 558 : 2 cyt c 553 : BChl/BPh = 2) and their mechanism for charge separation are very similar to those in BChl a-containing RCs; however, P960/sup +/, the oxidized form of the primary electron donor, is apparently not a symmetrical dimer of BChl b. The ''primary'' electron acceptor (X) is a quinone-iron complex, and I, the intermediary electron carrier between P960 and X, is BPh which interact(s) strongly with one or more of the other components in the RC. Comparison of the optical spectra of isolated RCs of the BChl b-containing bacteria, Rhodopseudomonas viridis and Thiocapsa pfennigii, with those of their intact cells shows that the BPh in the RC is not generated during the isolation procedure