Further Studies on the Photochemical Production of Reduced Triphosphopyridine Nucleotide and Adenosine Triphosphate by Fragmented Spinach Chloroplasts

Publisher Website
Google Scholar
Abstract
The effects of Mg ions, inorganic phosphate, adenosine diphosphate and tris (hydroxymethyl) aminomethane were studied on the rates of formation of reduced triphosphopyridine nucleotide and adenosine triphosphate by fragmented spinach chloroplasts. Chloroplasts have been shown to catalyze a phosphorylation in the presence of large amounts of photosynthetic pyridine nucleotide reductase, and no other added electron acceptor. Rates of photophosphorylation up to 108 umoles adenosine triphosphate/mg chlorophyll/hour were obtained. The phosphorylation was inhibited by anaerobic conditions and by 3-(p-chlorophenyl)-l,l-dimethylurea. Pyridine nucleotide transhydro-genase was shown to be involved. Under most experimental conditions the molar ratio of adenosine triphosphate to reduced triphosphopyridine nucleotide was unity, although ratios as high as 3.5 were obtained in the presence of high sodium chloride concentrations. The excess phosphorylation was concluded to be similar to that found in the presence of photosynthetic pyridine nucleotide reductase and no other exogenous cofactor.