A study of the kinetics and mechanism of yeast alcohol dehydrogenase with a variety of substrates.
1. The kinetics of oxidation of ethanol, propan-1-ol, butan-1-ol and propan-2-ol by NAD(+) and of reduction of acetaldehyde and butyraldehyde by NADH catalysed by yeast alcohol dehydrogenase were studied. 2. Results for the aldehyde-NADH reactions are consistent with a compulsory-order mechanism with the rate-limiting step being the dissociation of the product enzyme-NAD(+) complex. In contrast the results for the alcohol-NAD(+) reactions indicate that some dissociation of coenzyme from the active enzyme-NAD(+)-alcohol ternary complexes must occur and that the mechanism is not strictly compulsory-order. The rate-limiting step in ethanol oxidation is the dissociation of the product enzyme-NADH complex but with the other alcohols it is probably the catalytic interconversion of ternary complexes. 3. The rate constants describing the combination of NAD(+) and NADH with the enzyme and the dissociations of these coenzymes from binary complexes with the enzyme were measured.
D000433:1-Propanol; D000079:Acetaldehyde; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000440:Butanols; D055598:Chemical Phenomena; D002621:Chemistry; D002855:Chromatography, Thin Layer; D000431:Ethanol; D007700:Kinetics; D008433:Mathematics; D009243:NAD; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
D000440:Butanols; D009243:NAD; D000431:Ethanol; D000433:1-Propanol; D000429:Alcohol Oxidoreductases; D000079:Acetaldehyde