title: [Stereochemistry and mechanism of the methanol oxidase from Candida boidinii (author's transl)].
abstract: 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.
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D002175:Candida / Q000201:enzymology*; D003903:Deuterium; D000431:Ethanol / Q000378:metabolism; D007700:Kinetics; D000432:Methanol / Q000378:metabolism; D008968:Molecular Conformation; D013237:Stereoisomerism; D014316:Tritium
chemical_list: D014316:Tritium; D000431:Ethanol; D003903:Deuterium; D000429:Alcohol Oxidoreductases; D000432:Methanol
vernacular_title: Zur Stereochemie und zum Mechanismus der Methanol-Oxidase aus Candida boidinii