title: A hyperactive NAD(P)H:Rubredoxin oxidoreductase from the hyperthermophilic archaeon Pyrococcus furiosus.
abstract: NAD(P)H:rubredoxin oxidoreductase (NROR) has been purified from the hyperthermophilic archaeon Pyrococcus furiosus. The enzyme is exceedingly active in catalyzing the NADPH-dependent reduction of rubredoxin, a small (5.3-kDa) iron-containing redox protein that had previously been purified from this organism. The apparent Vmax at 80 degrees C is 20,000 micromol/min/mg, which corresponds to a kcat/Km value of 300,000 mM(-1) s(-1). The apparent Km values measured at 80 degrees C and pH 8.0 for rubredoxin, NADPH, and NADH were 50, 5, and 34 microM, respectively. The enzyme did not reduce P. furiosus ferredoxin. NROR is a monomer with a molecular mass of 45 kDa and contains one flavin adenine dinucleotide molecule per mole but lacks metals and inorganic sulfide. The possible physiological role of this hyperactive enzyme is discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: K
authors.initials: K
authors.lastname: Ma
authors.forename: M W
authors.initials: MW
authors.lastname: Adams
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D020027:Pyrococcus furiosus / Q000201:enzymology*
chemical_list: C023091:rubredoxin-NAD+ reductase; D009247:NADH, NADPH Oxidoreductases