title: Prolyl aminopeptidase is not a sulfhydryl enzyme: identification of the active serine residue by site-directed mutagenesis.
abstract: Prolyl aminopeptidase (PAP) has been classified as a sulfhydryl enzyme on the basis of its high sensitivity to p-chloromercuribenzoate and heavy metals. Recently, however, the possibility of PAP being instead a serine enzyme has been raised as a result of two observations--the conservation of some residues among the PAPs hitherto sequenced, and a similarity to some serine hydrolases. This is the first report describing an attempt to identify the active residue by site-directed mutagenesis. The pap genes from Bacillus coagulans and Aeromonas sobria, were used for the study. The changes made were Cys62Ser and Ser101Ala for the first enzyme, and Thr92Ala and Ser146Ala for the second. For both enzymes, only the changes made on the serine residues resulted in their complete inactivation, indicating that PAP is a serine peptidase.
authors.affiliation: School of Pharmaceutical Sciences, Nagasaki University.
authors.forename: A
authors.initials: A
authors.lastname: Kitazono
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: T
authors.initials: T
authors.lastname: Yoshimoto
mesh_terms: D000333:Aeromonas / Q000201:enzymology; D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry* / Q000235:genetics; D001407:Bacillus / Q000201:enzymology; D001483:Base Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017385:Sequence Homology; D012694:Serine / Q000737:chemistry*; D012697:Serine Endopeptidases / Q000737:chemistry
chemical_list: D012694:Serine; D000626:Aminopeptidases; C022450:prolyl aminopeptidase; D012697:Serine Endopeptidases