title: The Na(+)-translocating NADH:ubiquinone oxidoreductase from the marine bacterium Vibrio alginolyticus contains FAD but not FMN.
abstract: The Na(+)-translocating NADH:ubiquinone oxidoreductase from Vibrio alginolyticus was extracted from the bacterial membranes and purified by ion exchange chromatographic procedures. The enzyme catalyzed NADH oxidation by suitable electron acceptors, e.g. menadione, and the Na+ and NADH-dependent reduction of ubiquinone-1. Four dominant bands and a number of minor bands were visible on SDS-PAGE that could be part of the enzyme complex. Flavin analyses indicated the presence of FAD but no FMN in the purified enzyme. FAD but no FMN were also present in V. alginolyticus membranes. FAD is therefore a prosthetic group of the Na(+)-translocating NADH:ubiquinone oxidoreductase and FMN is not present in the enzyme. The FAD was copurified with the NADH dehydrogenase. The purified enzyme exhibited an absorption spectrum with a maximum at 450 nm that is typical for a flavoprotein. Upon incubation with NADH this absorption disappeared indicating reduction of the enzyme-bound FAD.
authors.affiliation: Mikrobiologisches Institut, Eidgenössische Technische Hochschule, ETH-Zentrum, Zürich, Switzerland.
authors.forename: X D
authors.initials: XD
authors.lastname: Pfenninger-Li
authors.forename: P
authors.initials: P
authors.lastname: Dimroth
mesh_terms: D002462:Cell Membrane / Q000201:enzymology; D042967:Electron Transport Complex I; D005486:Flavin Mononucleotide / Q000032:analysis*; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis* / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D014451:Ubiquinone / Q000378:metabolism; D014733:Vibrio / Q000201:enzymology*; D014812:Vitamin K / Q000378:metabolism
chemical_list: D014812:Vitamin K; D014451:Ubiquinone; D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I