[Pterin-protein complex and ferredoxin as possible components of a molecular complex in photosystem I]

Properties are studied of pterin-protein complex (PPC), possible precursor of ferredoxin in electrone transport chain PS-I. PPC is shown to form chelate complex with Fe ions which are capable to activate the process of light reduction of NADP+ by chloroplasts in the absence of ferrodoxin. A possibility of dark reduction of NADP+ with the participation of light pre-activated PPC is found. Two-step scheme of electrone transport from P700 to ferredoxin is supposed. The data obtained indicate that one of sites of electrone transport into interior part of tilakoid is located on the reduction side of PS-I. An additional possibility of NADP+ reduction with the participation of PPC-Fe in vivo is suggested.