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 Anacystis 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 [Pistorius, E. K. and Voss, H. (1980) Biochem. Biophys. Acta, 611, 227–240] as well as 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. Evidence is also presented that 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. Copyright © 1983, Wiley Blackwell. All rights reserved