Neumann R, Hevey R, Abeles R H
J Biol Chem. 1975 Aug 25;250(16):6362-7.
The action of plasma amine oxidase upon beta-Br-ethylamine beta-Cl-ethylamine, beta-OH-phenylethylamine, and beta-Cl-phenylethylamine was examined. Beta-Br-ethylamine is a substrate and irreversible inactivator of the enzyme. The enzyme becomes covalently labeled by the inactivator. Approximately 2 mol of inactivator are incorporated per mol of enzyme (MW 170,000). The reduced enzyme is not inactivated. The enzyme catalyzes the elimination of HCl from beta-Cl-phenylethylamine to produce phenylacetaldehyde. The rate of the elimination reaction is comparable to the normal oxidative reaction. We conclude that the occurrence of this elimination reaction establishes the ability of the enzyme to catalyze proton abstraction from C-1 of the substrate and that proton abstraction occurs during the catalytic oxidation normally catalyzed by plasma amine oxidase. Beta-Cl-ethylamine is only oxidized to corresponding aldehyde. Beta-OH-phenylethylamine is neither oxidized, nor does elimination occur. It is a competitive inhibitor in the oxidation of benzylamine and in the elimination of HCl from beta-Cl-phenylethylamine.
研究了血浆胺氧化酶对β-溴乙胺、β-氯乙胺、β-羟基苯乙胺和β-氯苯乙胺的作用。β-溴乙胺是该酶的底物和不可逆失活剂。该酶被失活剂共价标记。每摩尔酶（分子量170,000）约结合2摩尔失活剂。还原型酶不会失活。该酶催化从β-氯苯乙胺中消除HCl以生成苯乙醛。消除反应的速率与正常氧化反应相当。我们得出结论，这种消除反应的发生确立了该酶从底物的C-1位夺取质子的能力，并且质子夺取发生在血浆胺氧化酶通常催化的催化氧化过程中。β-氯乙胺仅被氧化为相应的醛。β-羟基苯乙胺既不被氧化，也不发生消除反应。它是苄胺氧化以及从β-氯苯乙胺中消除HCl的竞争性抑制剂。
