title: Inhibition of the cytochrome bd-terminated NADH oxidase system in Escherichia coli K-12 by divalent metal cations.
abstract: Co(II), Zn(II) and Cd(II) ions inhibited NADH oxidase activity in membranes prepared from two cytochrome bo'-deficient mutants of Escherichia coli K-12 with the following order of potency: Zn(II) > Cd(II) >> Co(II). The degree of inhibition exhibited by these metal ions was not diminished in membranes which contained elevated levels of the cytochrome bd complex, suggesting that the most sensitive site precedes this complex in the aerobic respiratory chain. For each of the metal ions studied, inhibition was determined to be of the non-competitive type. Based upon the efficacy with which EDTA alleviated inhibition, Co(II), Zn(II) and Cd(II) ions are proposed to inhibit NADH oxidase activity by binding to at least two sites in the respiratory chain with significantly different affinities.
authors.affiliation: Division of Life Sciences, King's College London, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Beard
authors.forename: M N
authors.initials: MN
authors.lastname: Hughes
authors.forename: R K
authors.initials: RK
authors.lastname: Poole
mesh_terms: D001665:Binding Sites; D002104:Cadmium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D003573:Cytochrome b Group; D003580:Cytochromes / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D045222:Electron Transport Chain Complex Proteins; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007700:Kinetics; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D010088:Oxidoreductases / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D002104:Cadmium; D003035:Cobalt; D004492:Edetic Acid; D010088:Oxidoreductases; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli; D015032:Zinc