The Reaction of Xanthine Oxidase with Molecular Oxygen
نویسندگان
چکیده
منابع مشابه
The reaction of xanthine oxidase with molecular oxygen.
The reaction of reduced xanthine oxidase with oxygen occurs in two distinct kinetic phases with the rate of the fast phase being about 10 times greater than that of the slow phase. Comparison of transient state and steady state kinetics demonstrates that only the fast phase of oxidation is catalytically significant. The time course of oxidation is quantitatively independent of the following fac...
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5-Ethynyluracil is a time-dependent and tight binding inhibitor of xanthine oxidase. The maximal value of the first-order rate constant for onset of inhibition is 0.01 s-1, and the concentration of 5-ethynyluracil which gives one-half of this value is 190 microM. Because the t1/2 for formation of active enzyme from inhibited enzyme is greater than 30 h in the absence of NADH, inhibition of xant...
متن کاملrole of oxygen-free radicals on the motility of rat ileum effects of xanthine plus xanthine oxidase
the major objective of the present study was to characterize the effects of oxidants generated b xanthine (x) plus xanthine oxidase (xo) on isolated rat ileum motility. the effects of three concentrations of x/xo on the basal tone of the rat ileum preparation were studied for 20 minutes. developed tensions were measured in mg/mg tissues and then expressed as percentage of baseline tension. also...
متن کاملTowards the reaction mechanism of xanthine oxidase from EPR studies.
Introduction EPR was the first spectroscopic method other than UV/visible spectroscopy to be applied systematically to investigations of the structure and functioning of metalloenzymes. The first such EPR studies of xanthine oxidase were reported in 1959 [l]. Since one reduced state of each of the four redox-active centres in the molecule is EPRactive, there is obviously considerable potential ...
متن کاملHydroxyl radical is not a product of the reaction of xanthine oxidase and xanthine. The confounding problem of adventitious iron bound to xanthine oxidase.
The reaction of xanthine and xanthine oxidase generates superoxide and hydrogen peroxide. In contrast to earlier works, recent spin trapping data (Kuppusamy, P., and Zweier, J.L. (1989) J. Biol. Chem. 264, 9880-9884) suggested that hydroxyl radical may also be a product of this reaction. Determining if hydroxyl radical results directly from the xanthine/xanthine oxidase reaction is important fo...
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ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1974
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(19)42427-7