title: Site-specific mutagenesis of two histidine residues in fatty acid ethyl ester synthase-III.
abstract: Human myocardial fatty acid ethyl ester synthase-III is a newly described acidic glutathione S-transferase that metabolizes both ethanol and carcinogens. Structure-function studies have not been performed relating these two distinct enzymatic activities. Since there are only two histidine residues in fatty acid ethyl ester synthase-III (His 72 and His 163), the role of each was examined by site-specific mutagenesis. Fatty acid ethyl ester synthase-III mutagenized at position 72 to contain either Gln, Pro or Ala had less than 5% of control glutathione S-transferase activity but retained fatty acid ethyl ester synthase activity under standard assay conditions. In contrast, substitution of histidine 163 with proline had no effect on glutathione S-transferase activity, but it slightly increased synthase activity. Thus, this study indicates that histidine plays a differential role in fatty acid ethyl ester synthase III depending on the nucleophilic substrate.
authors.affiliation: Department of Medicine, Jewish Hospital of St. Louis, Washington University Medical Center, Missouri.
authors.forename: P S
authors.initials: PS
authors.lastname: Bora
authors.forename: X
authors.initials: X
authors.lastname: Wu
authors.forename: L G
authors.initials: LG
authors.lastname: Lange
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D005982:Glutathione Transferase / Q000235:genetics; D006639:Histidine; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000201:enzymology; D009838:Oligodeoxyribonucleotides; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
chemical_list: D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D006639:Histidine; D000217:Acyltransferases; D005982:Glutathione Transferase; C043403:fatty acyl ethyl ester synthase