Regulation by Pyruvate Kinase and Phosphatase of Inorganic Phosphate Incorporation during Photophosphorylation

A study of the effect on the photophosphorylating system of those enzymes, which transform phosphoric esters, may be of great importance for discovering a mechanism in the regulation of some stage of the bioenergetic processes. Enzymes added to intact chloroplasts may interact with intermediates of photophosphorylation or with enzymes of this system, and thus evoke changes in the rate of inorganic phosphate incorporation during photophosphorylation. In this connection the effects of three enzymes — acid and alkaline phosphatases and pyruvate kinase — on the rate of photophosphorylation were studied. The enzymes were introduced into suspensions of chloroplasts at the beginning of or after definite periods of illumination. In the course of the experiment changes in inorganic phosphate and nucleotides were determined.