[Effect of endogenous phosphate on electron transfer in chloroplasts]

The chloroplasts with an extremely low content of endogeneous inorganic phosphate have been isolated by appropriate physiological pretreatment of pea or bean plants (intense illumination at a moderately low temperature during blossoming). The electron transport activity of these preparations as measured by ferricyanide or methylred photoreduction is almost completely blocked until exogeneous phosphate is added to the incubation mixture. Low concentrations of phosphate are also necessary for maintaining the stability of chloroplasts and for inhibition of the light-induced degradation of the photosynthetic apparatus.