title: Role of ubiquinone-10 in electron transport system of chromatophores from Rhodospirillum rubrum.
abstract: The role of ubiquinone-10 in the activities for the reduction of free cytochrome c2 and bound cytochrome cc' by succinate was studied with chromatophores from a blue-green mutant (G-9) of Rhodospirillum rubrum. 1. By a single extraction with isooctane, approximately 90% of ubiquinone-10 was easily removed from the chromatophores. In the extracted chromatophores, the activity for succinate-cytochrome c2 reduction decreased to 5-10% of the original activity. This depressed activity was mostly restored by adding ubiquinone-10. The remaining quinone was hardly extractable, even by repeated extractions. With repeatedly extracted chromatophores, the activity for succinate-cytochrome c2 reduction was mostly restored to the same extent as with once-extracted chromatophores, whereas the extent of inhibtion of the activity by antimycin A gradually fell. 2. In isooctane-extracted chromatophores, the activity for the reduction of bound cytochrome cc' by succinate under anaerobic conditions decreased to 35 to 95% of the original level. With chromatophores in which the remaining activity was as low as 40% of the original level, the activity was partially restored by adding ubiquinone-10, but this was not the case with chromatophores in which the remaining activity was higher than approximately 50% of the original level.
mesh_terms: D000473:Alkanes / Q000494:pharmacology; D000693:Anaerobiosis; D000968:Antimycin A / Q000494:pharmacology; D020130:Bacterial Chromatophores / Q000378:metabolism*; D003579:Cytochrome Reductases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004579:Electron Transport; D012247:Rhodospirillum rubrum / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D014451:Ubiquinone / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000473:Alkanes; D003574:Cytochrome c Group; D013386:Succinates; D014451:Ubiquinone; D000968:Antimycin A; D003579:Cytochrome Reductases