title: Quinone-enhanced reduction of nitric oxide by xanthine/xanthine oxidase.
abstract: The quinones 1,4-naphthoquinone, methyl-1,4-naphthoquinone, tetramethyl-1,4-benzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,6-dimethylbenzoquinone, 2,6-dimethoxybenzoquinone, and 9,10-phenanthraquinone enhance the rate of nitric oxide reduction by xanthine/xanthine oxidase in nitrogen-saturated phosphate buffer (pH 7.4). Maximum initial rates of NO reduction (V(max)) and the amount of nitrous oxide produced after 5 min of reaction increase with quinone one- and two-electron redox potentials measured in acetonitrile. One of the most active quinones of those studied is 9,10-phenanthraquinone with a V(max) value 10 times larger than that corresponding to the absence of quinone, under the conditions of this work. Because NO production is enhanced under hypoxia and under certain pathological conditions, the observations obtained in this work are very relevant to such conditions.
authors.affiliation: Department of Chemistry, University of Puerto Rico at Humacao, Humacao, Puerto Rico 00791.
authors.forename: Pedro
authors.initials: P
authors.lastname: Sanchez-Cruz
authors.forename: Antonio E
authors.initials: AE
authors.lastname: Alegría
mesh_terms: D007700:Kinetics; D009569:Nitric Oxide / Q000737:chemistry* / Q000378:metabolism; D009609:Nitrous Oxide / Q000032:analysis; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000737:chemistry; D011809:Quinones / Q000737:chemistry*; D014969:Xanthine Oxidase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010616:Phenanthrenes; D011809:Quinones; D009569:Nitric Oxide; C005399:9,10-phenanthrenequinone; D014969:Xanthine Oxidase; D009609:Nitrous Oxide