title: Kinetics and reaction mechanism of yeast alcohol dehydrogenase with long-chain primary alcohols.
abstract: Kinetic studies of yeast alcohol dehydrogenase with NAD+ and ethanol, hexanol or decanol as substrates invariably result in non-linear Lineweaver-Burk plots if the alcohol is the variable substrate. The kinetic coefficients determined from secondary plots are consistent with an 'equilibrium random-order' mechanism for extremely low alcohol concentrations and for all alcohols, the transformation of the ternary complexes being the rate-limiting step of the reaction. This mechanism also applies to long-chain substrates at high concentrations, whereas the rate of the ethanol-NAD+ reaction at high ethanol concentrations is determined by the dissociation of the enzyme-NADH complex. The dissociation constants for the enzyme-NAD+ complex and for the enzyme-alcohol complexes obtained from the kinetic quotients satisfactorily correspond to the dissociation constants obtained by use of other techniques. It is suggested that the non-linear curves may be attributed to a structural change in the enzyme itself, caused by the alcohol.
mesh_terms: D000418:Albumins / Q000494:pharmacology; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000438:Alcohols / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology; D000441:Hexanols / Q000378:metabolism; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D000418:Albumins; D000438:Alcohols; D000441:Hexanols; D009243:NAD; D000431:Ethanol; D000429:Alcohol Oxidoreductases; D005978:Glutathione