Inhibitor Studies on Carbon Dioxide Fixation, Adenosine Triphosphate Formation, & Triphosphopyridine Nucleotide Reduction by Spinach Chloroplasts

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Abstract
-I. [long dash]The effects of Antimycin A, 3-(p-chloro-phenyl)-l,l-dimethylurea, m-chlorocarbonyl cyanide phenylhydrazone, 2-heptyl-4-hydroxyquinoline-N-oxide, and 2-nonyl-4-hydroxyquinoline-N-oxide were studied on triphosphopyridine nucleotide reduction, "cyclic" and "non-cyclic" photophosphorylation, and carbon dioxide assimilation by spinach chloroplasts. II. 3-(p-Chlorophenyl)-1,1-dimethylureaandthe hydroxyquinoline compounds inhibited triphosphopyridine nucleotide re-duction and the associated phosphorylation but the effect could be overcome by the addition of 2,6-dichlorophenol-indophenol and ascorbate. Ascorbate overcame the inhibition of carbon dioxide fixation. III. m-Chlorocarbonyl cyanide phenylhydrazone was a potent uncoupler of phosphorylation from electron transfer. It inhibited CO2 fixation but this effect could be overcome by the addition of fructose-l,6-diphosphate. IV. Antimycin A had relatively little effect on any of the processes examined.