Effects of Mn2+, Ca2+ and chlorpromazine on photosystem II of Anacystis nidulans. An attempt to establish a functional relationship of amino acid oxidase to photosystem II

Abstract

Washing with EDTA changes the specificity of A. nidulans particles having photosystem II activities for activation by cations. A specific requirement for Mn2+ and a somewhat lower specificity for Ca2+ can be demonstrated in the EDTA-washed particles. Both ions must be added to reconstitute the system evolving O2 in the light. EDTA-washed particles retain the L-amino acid oxidase with high specificity for the basic L-amino acids and the ability to reduce 2,6-dichloroindophenol with diphenylcarbazide as a donor in the light. The latter reaction, which does not require added cations, can be inhibited by chlorpromazine, and this inhibition can be partially relieved by Ca2+ ions. The L-amino acid oxidase is inhibited by chlorpromazine, and this inhibition can be relieved by L-arginine in much the same way as the inhibition of the enzyme by Ca2+ ions can be relieved by L-arginine. The data are compatible with, but do not prove, an involvement of the L-amino-acid oxidase in the redox reactions of photosystem II of A. nidulans.