Photophosphorylation during Chloroplast Development in Red Kidney Bean. I. Characterization of the Mature System and the Effect of BSA and Sulfhydryl Reagents.

Optimal conditions were determined for photophosphorylation and reduction in mature chloroplasts from Phaseolus vulgaris var. Red Kidney. Bovine serum albumin (BSA) at 1 mg/ml and various sulfhydryl reagents (0.1-0.5 mm) greatly enhanced cyclic and noncyclic phosphorylation, but had little effect on photoreduction. BSA and reduced glutathione also stimulated cyclic phosphorylation in spinach chloroplasts. BSA was needed in the reaction from the start to provide high rates of phosphorylation. BSA also protected against atebrin uncoupling but not against uncoupling by ammonium ions or inhibition by 3,-(3,4-dichlorophenyl)-1,1-dimethylurea. Similarly, BSA and glutathione protected against atebrin inhibition of cyclic phosphorylation. Chloroplasts incubated at 0 degrees rapidly lost the ability to catalyze phosphorylation and BSA did not protect against inactivation.