title: Characterization of an exceedingly active NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima.
abstract: An NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima was purified. The enzyme was very active in catalyzing the reduction of oxygen to hydrogen peroxide with an optimal pH value of 7 at 80 degrees C. The V(max) was 230 +/- 14 mumol/min/mg (k(cat)/K(m) = 548,000 min(-1) mM(-1)), and the K(m) values for NADH and oxygen were 42 +/- 3 and 43 +/- 4 muM, respectively. The NADH oxidase was a heterodimeric flavoprotein with two subunits with molecular masses of 54 kDa and 46 kDa. Its gene sequences were identified, and the enzyme might represent a new type of NADH oxidase in anaerobes. An NADH-dependent peroxidase with a specific activity of 0.1 U/mg was also present in the cell extract of T. maritima.
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Xianqin
authors.initials: X
authors.lastname: Yang
authors.forename: Kesen
authors.initials: K
authors.lastname: Ma
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry; D017421:Sequence Analysis; D013696:Temperature; D020124:Thermotoga maritima / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D009097:Multienzyme Complexes; D021122:Protein Subunits; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D010100:Oxygen