ENZYMOLOGY OF ETHANOL AND ACETALDEHYDE METABOLISM IN MAMMALS

Ethanol or ethyl alcohol is a molecule that, in mammals, is naturally present at low concentrations due to its production by gastrointestina l flora fermentation activity. However, it is remarkable that this met abolite, with a clearly minor role in regular vertebrate metabolism, c an be oxidized into acetaldehyde through several enzymatic and nonenzy matic mechanisms, which comprise the activity of more than ten enzymes and isozymes, many of them broadly distributed in different species a nd tissues. In correspondence, acetaldehyde can also be oxidized into acetate through several enzymatic pathways that involve about ten enzy mes and isozymes which also have a broad distribution. In this article , a complete review of the aforementioned metabolic pathways is elabor ated. From this group, the participation and wide distribution of alco hol dehydrogenase and aldehyde dehydrogenase systems are emphasized. T he mechanisms of reaction, kinetic characteristics and physiological r elevance are described, and finally, the possible physiological role o f these enzymatic systems as responsible to synthesize or catabolize s everal endogenous metabolites that regulate growth, metabolism, differ entiation and neuroendocrine function in mammals are discussed.