title: The role of the S1 binding site of carboxypeptidase M in substrate specificity and turn-over.
abstract: The influence of the P1 amino acid on the substrate selectivity, the catalytic parameters K(m) and k(cat), of carboxypeptidase M (CPM) (E.C. 3.4.17.12) was systematically studied using a series of benzoyl-Xaa-Arg substrates. CPM had the highest catalytic efficiency (k(cat)/K(m)) for substrates with Met, Ala and aromatic amino acids in the penultimate position and the lowest with amino acids with branched side-chains. Substrates with Pro in P1 were not cleaved in similar conditions. The P1 substrate preference of CPM differed from that of two other members of the carboxypeptidase family, CPN (CPN/CPE subfamily) and CPB (CPA/CPB subfamily). Aromatic P1 residues discriminated most between CPM and CPN. The type of P2 residue also influenced the k(cat) and K(m) of CPM. Extending the substrate up to P7 had little effect on the catalytic parameters. The substrates were modelled in the active site of CPM. The results indicate that P1-S1 interactions play a role in substrate binding and turn-over.
authors.affiliation: Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. kathleen.deiteren@ua.ac.be
authors.forename: Kathleen
authors.initials: K
authors.lastname: Deiteren
authors.forename: Georgiana
authors.initials: G
authors.lastname: Surpateanu
authors.forename: Kambiz
authors.initials: K
authors.lastname: Gilany
authors.forename: Johan L
authors.initials: JL
authors.lastname: Willemse
authors.forename: Dirk F
authors.initials: DF
authors.lastname: Hendriks
authors.forename: Koen
authors.initials: K
authors.lastname: Augustyns
authors.forename: Yves
authors.initials: Y
authors.lastname: Laroche
authors.forename: Simon
authors.initials: S
authors.lastname: Scharpé
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lambeir
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D058851:GPI-Linked Proteins; D007700:Kinetics; D008666:Metalloendopeptidases / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D017931:DNA Primers; D058851:GPI-Linked Proteins; D011994:Recombinant Proteins; C058479:carboxypeptidase M; D008666:Metalloendopeptidases