The catalytic specificity of liver alcohol dehydrogenase: vitamin A alcohol and vitamin A aldehyde activities.

Abstract

Liver alcohol dehydrogenase (LADH, E.C.I. 1.1.1) is an NAD+/NADH dependent enzyme with a broad substrate specificity. It catalyzes the reversible oxidation of a wide variety of alcohols to the corresponding aldehydes and ketones, as well as the oxidation of certain aldehydes to their carboxylic acids (Jornvall, 1970; Branden, et al., 1975; Klinman, 1981; Eklund and Branden, 1983; Zeppezauer, 1986; Pocker, et al., 1986; Pettersson, 1987; Pocker, 1989). The enzyme’s primary and tertiary structures have been determined, as have its catalytic mechanisms, isozyme differences and evolutionary divergences (Eklund and Branden, 1987; Eklund, et al., 1987; Pocker, 1989, Light, et al., 1992). Although the physiological substrates of alcohol dehydrogenase are unknown, this enzyme catalyzes the interconversion of all-trans retinol, Vitamin A alcohol and all-trans retinal, Vitamin A aldehyde, Figure 1 (Pocker et al., 1987). In addition, liver alcohol dehydrogenase catalyzes the oxidation of all-trans retinal to the corresponding retinoic acid (Pocker et al., 1987).