FLAVIN COMPOUNDS AS AGENTS FOR THE OXIDATION OF PLASTOCYANIN IN BLUE LIGHT

Abstract—Flavins, flavin nucleotides and selected flavoproteins have been compared in a reaction using blue light. in which plastocyanin is oxidized as the flavin is photoreduced. Per unit of light absorbed. flavin mononucleotide is more effective than flavin adenine dinucleotide, ribotlavin or lumiflavin. Of the flavoproteins tested, diaphorase from Clostridium kluyveri was most effective, but was less active than free flavin mononucleotide. The oxidation of plastocyanin requires aerobic conditions. and appears to be mediated by the production of singlet oxygen when the flavin is irradiated.