Purification and properties of cytochrome bo-type ubiquinol oxidase from a marine bacterium Vibrio alginolyticus.

Ubiquinol oxidase was extracted from membranes of a marine bacterium Vibrio alginolyticus with a nonionic detergent Liponox DCH and was purified about 130-fold by DEAE-Sephacel, DEAE-5PW and Sephacryl S-300. The purified ubiquinol oxidase was composed of three subunits with apparent M(r) of 79, 36 and 13 kDa on SDS-polyacrylamide gel electrophoresis. The oxidase contained cytochrome b, cytochrome o and copper atoms. The presence of heme O was confirmed by reverse-phase HPLC analysis. Ubiquinol-1, duroquinol and tetramethylphenylene diamine, but not horse heart reduced cytochrome c, were oxidized by this enzyme. The oxidase required no salts for activity and was stimulated by several detergents and by diphosphatidyl glycerol. The activity was strongly inhibited by KCN, 2-n-heptyl-4-hydroxyquinoline N-oxide and ZnSO4. These properties were essentially similar to those of cytochrome bo-type ubiquinol oxidase from Escherichia coli, suggesting that the bo-type ubiquinol oxidase is functioning as a proton pump in the marine V. alginolyticus.