Studies on the Photoactivation of the Water-Oxidizing Enzyme

Abstract
In weak yet optimal light intensity, complete photoactivation of the water-oxidizing enzyme in NH2OH-extracted wheat (Triticum aestivum, var Oasis) leaf segments could be obtained only after long dark preincubation. Photoactivation was not affected by ethylenediaminetetraacetate or inhibitors of photophosphorylation and protein synthesis, but was partially inhibited by a divalent cation ionophore. Complete photoactivation required ligation of ∼4 Mn by the water oxidizing enzyme.