title: Atypical human liver alcohol dehydrogenase: the beta 2-Bern subunit has an amino acid exchange that is identical to the one in the beta 2-Oriental chain.
abstract: The "atypical' human liver alcohol dehydrogenase dimer, homogeneous for beta 2-Bern chains, was isolated from human liver of Caucasian individuals. It is derived from an allelic variant at the ADH2 gene locus and exhibits a considerably higher specific activity and lower pH optimum than its "typical' counterpart (isoenzyme beta 1 beta 1) from the beta 1-chain predominant in Caucasians. Peptides were prepared by trypsin or CNBr cleavage, and were purified by exclusion chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC). Structural analysis of the peptides showed that beta 2-Bern differs at one position from beta 1. Thus, Arg-47 in beta 1 is substituted by His in beta 2-Bern. This exchange, compatible with a one-base mutation, explains all functional differences by altered interactions with the pyrophosphate moiety of the coenzyme. The difference is also structurally identical to that found for another atypical beta 2-subunit, the beta 2-Oriental type of major Asian occurrence, linking these two atypical forms of human alcohol dehydrogenase.
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D000596:Amino Acids / Q000032:analysis; D005796:Genes; D014644:Genetic Variation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin; D044465:White People
chemical_list: D000596:Amino Acids; D007527:Isoenzymes; D046911:Macromolecular Substances; D010446:Peptide Fragments; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D014357:Trypsin