title: Two regimens of electrogenic cyclic redox chain operation in chromatophores of non-sulfur purple bacteria. A study using antimycin A.
abstract: Antimycin A causes a biphasic suppression of the light-induced membrane potential generation in Rhodospirillum rubrum and Rhodopseudomonas sphaeroides chromatophores incubated anerobically. The first phase is observed at low antibiotic concentrations and is apparently due to its action as a cyclic electron transfer inhibitor. The second phase is manifested at concentrations which are greater than 1--2 muM and is due to uncoupling that may be connected with an antibiotic-induced dissipation of the electrochemical H+ gradient across the chromatophore membrane. The inhibitory effect of antimycin added at low concentrations under aerobic conditions is removed by succinate to a large extent. It is expected that the electrogenic cyclic redox chain in the bacterial chromatophores incubed under conditions of continuous illumination may function at two regimes: (1) as a complete chain involving all the redox components, and (2) as a shortened chain involving only the P-870 photoreaction center, ubiquinone and cytochrome c2.
mesh_terms: D000693:Anaerobiosis; D000968:Antimycin A / Q000494:pharmacology*; D020130:Bacterial Chromatophores / Q000187:drug effects / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004579:Electron Transport; D007700:Kinetics; D010084:Oxidation-Reduction; D012242:Rhodobacter sphaeroides / Q000187:drug effects / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000187:drug effects / Q000378:metabolism*; D013775:Tetraphenylborate / Q000378:metabolism
chemical_list: D013775:Tetraphenylborate; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000968:Antimycin A