title: Structural relationships among aldehyde dehydrogenases.
abstract: Two functional regions of liver aldehyde dehydrogenase were characterized before; other structures of homologous parts from isoenzymes have now been determined to obtain further information on the isoenzyme relationships. In a 22-residue region from the horse cytoplasmic and mitochondrial isoenzymes, substitutions occur at 12 positions, including a continuous six-residue portion characterized by non-conservative changes. In contrast, the same structure from the cytoplasmic isoenzyme shows exchanges at only three positions when compared to its counterpart from human cytoplasm. A similar estimate of substitution frequency between species is obtained from a larger sampling at 236 positions. Thus, the isoenzyme difference between aldehyde dehydrogenases from the same species is about five-fold greater than the species difference between corresponding isoenzymes. Hence, the relationship between cytoplasmic and mitochondrial aldehyde dehydrogenases, while recognizable, is distant. This is compatible with the fact that a property such as high sensitivity to disulfiram is a characteristic of only the cytoplasmic isoenzyme.
mesh_terms: D000444:Aldehyde Dehydrogenase; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003593:Cytoplasm / Q000201:enzymology; D006736:Horses; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D010446:Peptide Fragments / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D007527:Isoenzymes; D010446:Peptide Fragments; D000445:Aldehyde Oxidoreductases; D000444:Aldehyde Dehydrogenase