The co-oxidation of ammonia to nitrite during the aerobic xanthine oxidase reaction.
The xanthine oxidase reaction causes a co-oxidation of NH3 to NO2-, which was inhibitable by superoxide dismutase, catalase, hydroxyl radical scavengers, or by the chelating agents, desferrioxamine or diethylene triaminepentaacetic acid. Hydroxylamine was oxidized to NO2- much more rapidly than was NH3, and in this case superoxide dismutase or the chelating agents inhibited but catalase or the HO. scavengers did not. Hydrazine was not detectably oxidized to NO2-, and NO2- was not oxidized to NO3-, by the xanthine oxidase reaction. These results are accommodated by a reaction scheme involving (a) the metal-catalyzed production of HO. from O2- + H2O2; (b) the oxidation of H3N to H2N. by OH.; (c) the coupling of H2N. with O2- to yield peroxylamine, which hydrolyzes to hydroxylamine plus H2O2; (d) the metal-catalyzed oxidation of HO-NH2 to (Formula: see text), which couples with O2- to yield (Formula: see text), which finally dehydrates to yield NO2-.
D000641:Ammonia; D006834:Hydrazines; D019811:Hydroxylamine; D006898:Hydroxylamines; D009573:Nitrites; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000494:pharmacology*
D006834:Hydrazines; D006898:Hydroxylamines; D009573:Nitrites; C029424:hydrazine; D019811:Hydroxylamine; D000641:Ammonia; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase