Carboxymethylated Liver Alcohol Dehydrogenase

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Abstract
The rate constants for NADH binding and dissociation for carboxymethylated [horse liver] alcohol dehydrogenase [EC 1.1.1.1] were determined and compared to those for the native enzyme. Steady-state and transient kinetic experiments have shown that H transfer step is rate-determining for oxidation of ethanol by carboxymethylated alcohol dehydrogenase. The rate constant of 0.19 s-1 is considerably slower than that for the native enzyme. The steady-state parameter, V/[E], was obtained for each of a series of alcohols and correlated with the Taft substituent parameter [.sigma.*]. The linear relationship obtained indicates that the same step, H transfer, is rate-determining for all the alcohols. The .rho.* value [slope of straight line from graph of log of V/[E] vs. .sigma.*] obtained is the same as for the native enzyme; the implications of this for the mechanism of H transfer are discussed.