Energy coupling to ATP synthesis and pyridine nucleotide transhydrogenase in chromatophores from photosynthetic bacteria A ‘dual‐consumer’ test for localised interactions with electron transport components

Abstract

The rate of ATP synthesis and the rate of pyridine nucleotide transhydrogenase were recorded in parallel experiments in steady‐state conditions following the onset of illumination in chromatophores of Rhodobacter capsulatus (formerly Rhodopseudomonas capsulata). The transhydrogenase rate was more resistant than the ATP synthesis rate to inhibition by antimycin A and myxothiazol, the uncoupler, carbonyl cyanide p‐trifluoromethoxyphenylhydrazone and the combination of valinomycin with nigericin in the presence of K⁺. The relationship between the transhydrogenase rate and the ATP synthesis rate was not influenced by the nature of the inhibitor. These data suggest that the ATP synthase and the transhydrogenase are differentially regulated by Δp but not by local interactions with components of the electron transport chain.