Effect of substrate structure on the pre-steady-state kinetics of oxidation by liver alcohol dehydrogenase. A correlation with the Taft sigma parameter.
The oxidation of a series of primary alcohols by liver alcohol dehydrogenase has been studied under conditions of [S]o greater than [E]o using the stopped-flow method. A biphasic process, with exponential rise to a steady state, was observed for most of the alcohols and the rate constants for the transient phase were determined. No transient phase could be detected for 2-chloroethanol and 2-nitroethanol and steady-state measurements were made for these alcohols. The rate constants for the hydrogen transfer step were obtained from the pre-steady-state rate constants for the various alcohols and correlated with the Taft sigma constant. The (see article) value obtained (-1.8) is consistent with rate-limiting hydride transfer coupled with removal of the hydroxyl proton by a suitable basic group on the enzyme. A possible identity for this group is suggested.
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000818:Animals; D000431:Ethanol / Q000031:analogs & derivatives; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008433:Mathematics; D008623:Mercaptoethanol; D009574:Nitro Compounds; D020005:Propanols; D013329:Structure-Activity Relationship
D009574:Nitro Compounds; D020005:Propanols; D000431:Ethanol; D008623:Mercaptoethanol; D000429:Alcohol Oxidoreductases