COPPER INHIBITION OF PHOTOSYSTEM II ACTIVITY IN THE CYANOPHAGE AS-1-RESISTANT MUTANT

Abstract

Copper inhibited the photoreduction of DCPIP (PS II activity) in a spheroplast preparation of cyanophage AS-1-resistant mutant (An/AS-1). The inhibitory action of Cu²⁺ was reversed by supplementation with manganese but not with DPC. The results suggest that the site of inhibition was either between the Mn²⁺ and DPC donation site(s) or close to DPC donation site. Protection of the Hill activity by EDTA further suggestes that Cu²⁺ interacted with the reaction center.