title: Identification of a catalytically essential nucleophilic residue in sheep liver cytoplasmic aldehyde dehydrogenase.
abstract: Sheep liver cytoplasmic aldehyde dehydrogenase was labelled by reaction with the substrate p-nitrophenyl di[14C]methylcarbamate. After tryptic digestion and peptide fractionation the labelled residue was identified as Cys-302. This is the first unequivocal identification of the essential enzymic nucleophile in the esterase activity of aldehyde dehydrogenase. By implication, Cys-302 is probably also the residue that is acylated by aldehyde substrates and the first residue that is modified by disulfiram.
authors.affiliation: Department of Chemistry and Biochemistry, Massey University, Palmerston North, New Zealand.
authors.forename: T M
authors.initials: TM
authors.lastname: Kitson
authors.forename: J P
authors.initials: JP
authors.lastname: Hill
authors.forename: G G
authors.initials: GG
authors.lastname: Midwinter
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002219:Carbamates / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry*; D003593:Cytoplasm / Q000201:enzymology; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D012756:Sheep; D014357:Trypsin
chemical_list: D002219:Carbamates; D010446:Peptide Fragments; C068366:4-nitrophenyl dimethylcarbamate; D000444:Aldehyde Dehydrogenase; D014357:Trypsin; D003545:Cysteine