Periplasmic electron carriers and photo-induced electron transfer in the photosynthetic bacterium Ectothiorhodospira sp.

A detailed analysis of the periplasmic electron carriers of the photosynthe tic bacterium Ectothiorhodospira sp. has been performed. Two low mid-point redox potential electron carriers, cytochrome c' and cytochrome c, are dete cted. A high potential iron-sulfur protein is the only high mid-point redox potential electron transfer component present in the periplasm. Analysis o f light-induced absorption changes shows that this high potential iron-sulf ur protein acts in vivo as efficient electron donor to the photo-oxidized h igh potential heme of the Ectothiorhodospira sp. reaction center.