title: Active-site residues of procarboxypeptidase Y are accessible to chemical modification.
abstract: The accessibility of the active-site cleft of procarboxypeptidase Y from Saccharomyces cerevisiae has been studied by chemical modifications of two specific amino-acid residues. Previous studies have shown that these residues, Cys-341 and Met-398 in the mature enzyme, are located in the S1 and S'1 substrate binding sites, respectively, of carboxypeptidase Y. We have found that these residues also in proCPY are accessible to modification with fairly bulky reagents and in the case of Met-398 the rate of modification is even faster than in carboxypeptidase Y. While the catalytic serine in the mature enzyme reacts with diisopropylfluorophosphate, this is not the case for procarboxypeptidase Y.
authors.affiliation: Carlsberg Laboratory, Department of Yeast Genetics, Copenhagen Valby, Denmark.
authors.forename: S O
authors.initials: SO
authors.lastname: Sørensen
authors.forename: J R
authors.initials: JR
authors.lastname: Winther
mesh_terms: D000098:Acetophenones / Q000378:metabolism; D001665:Binding Sites; D002268:Carboxypeptidases / Q000737:chemistry* / Q000187:drug effects; D043402:Cathepsin A; D004792:Enzyme Precursors / Q000737:chemistry* / Q000494:pharmacology; D004795:Enzyme Stability; D007531:Isoflurophate / Q000494:pharmacology; D008627:Mercuric Chloride / Q000494:pharmacology; D010663:Phenylmercury Compounds / Q000494:pharmacology; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D000098:Acetophenones; D004792:Enzyme Precursors; D010663:Phenylmercury Compounds; D029701:Saccharomyces cerevisiae Proteins; D007531:Isoflurophate; D008627:Mercuric Chloride; C013190:phenacyl bromide; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; C022633:serine carboxypeptidase; C008859:phenylmercuric chloride