Human Aldehyde Dehydrogenase E3

Abstract

The human “low Km” aldehyde dehydrogenases, E1, E2 and E3 share many common catalytic features. These include NAD as coenzyme, broad substrate specificity, low micro-molar Km values for short chain aliphatic aldehydes, and similar Km values and maximal velocities with substrates such as imidazole acetaldehyde and the metabolites of monoamines like serotonin, dopamine and norepinephrine (Ambroziak and Pietruszko, 1991). All three isozymes also catalyze the dehydrogenation of aminoaldehydes; however, the Km values of the E3 isozyme for these compounds are considerably lower (5 μM for γ-aminobutyraldehyde, Ambroziak and Pietruszko, 1991) than those of E1 and E2 isozymes (Km values for γ-aminobutyraldehyde, 800 μM and 500 μM, respectively, Ambroziak and Pietruszko, 1987). Work on enzymes like E1 and E2 from other species has demonstrated that both El-like (class 1) and E2-like (class 2) enzymes can catalyze the dehydrogenation of retinal to retinoic acid (Chen et al., 1994). There is good evidence for the involvement of the class 1 enzyme in mammalian eye development (McCaffery et al., 1991; Godbout et al., 1996). This enzyme may also be involved in prostaglandin metabolism (Westlund et al., 1994).