Kraus A, Simon H
Hoppe Seylers Z Physiol Chem. 1975 Oct;356(10):1477-84.
Under nitrogen atmosphere, methanol oxidase isolated from Candida boidinii catalyzes no hydrogen exchange of ethanol. Reactions with (1R)[1-3H]ethanol or (1S)[1-3H]ethanol occur stereoselectively. The ratio of hydrogen abstraction in the oxidation of ethanol is about 7:1 in favor of the pro R hydrogen atom. The isotope effect kH/k3H is 2 - 2.5 for (1R)[1-3H]ethanol. The isotope effects on Km and V have been determined for four different deuterium-labelled ethanols. The Km for [2H3]methanol is nearly twice that for CH3OH. That is about the same ratio as for ethanol/methanol. For the oxidation of CH3OH and 2H3COH, the ratio of VH/V2H3 = 2.44, while the ratio for methanol/ethanol is only 1.3. It has been conformed that catalase from bovine liver eliminates only the pro R hydrogen atom from ethanol. The isotope effect for the catalase-catalyzed oxidation of (1R)[1-3H]ethanol is 2.1.
在氮气氛围下，从博伊丁假丝酵母中分离出的甲醇氧化酶不会催化乙醇的氢交换反应。与(1R)[1-³H]乙醇或(1S)[1-³H]乙醇的反应具有立体选择性。乙醇氧化过程中氢提取的比例约为7:1，有利于前手性R氢原子。(1R)[1-³H]乙醇的同位素效应kH/k³H为2 - 2.5。已测定了四种不同氘标记乙醇的Km和V的同位素效应。[2H₃]甲醇的Km几乎是CH₃OH的两倍。这与乙醇/甲醇的比例大致相同。对于CH₃OH和2H₃COH的氧化，VH/V2H₃的比例为2.44，而甲醇/乙醇的比例仅为1.3。已证实牛肝过氧化氢酶仅从乙醇中去除前手性R氢原子。(1R)[1-³H]乙醇的过氧化氢酶催化氧化的同位素效应为2.1。
