title: Dipeptidyl peptidase III is a zinc metallo-exopeptidase. Molecular cloning and expression.
abstract: We have purified dipeptidyl peptidase III (EC 3.4.14.4) from human placenta. It had a pH optimum of 8.8 and readily hydrolysed Arg-Arg-beta-naphthylamide. Monoamino acid-, Gly-Phe-, Gly-Pro- and Bz-Arg-beta-naphthylamides were not hydrolysed at all. The enzyme was inhibited by p-chloromercuriphenylsulphonic acid, metal chelators and 3,4-dichloroisocoumarin and contained 1 mol of zinc per mol of enzyme. The zinc dissociation constant was 250 fM at pH 7. 4 as determined by the zinc binding study. We isolated, by immunological screening of a Uni-ZAP XR cDNA library constructed from rat liver mRNA species, a cDNA clone with 2633 bp encoding the rat enzyme. The longest open reading frame encodes a 827-residue protein with a theoretical molecular mass of 92790 Da. Escherichia coli SOLR cells were infected with the pBluescript phagemid containing the cloned cDNA and established the overexpression of a protein that hydrolysed Arg-Arg-beta-naphthylamide. The recombinant protein was purified and the amino acid sequence of the protein was confirmed. We presumed that the putative zinc-binding domain involved in catalysis was present in the recombinant enzyme. It was a novel zinc-binding motif in that one amino acid residue was inserted into the conserved HEXXH motif characteristic of the metalloproteinases.
authors.affiliation: Department of Oral Biochemistry, Matsumoto Dental College, Shiojiri, Nagano 399-07, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fukasawa
authors.forename: K M
authors.initials: KM
authors.lastname: Fukasawa
authors.forename: M
authors.initials: M
authors.lastname: Kanai
authors.forename: S
authors.initials: S
authors.lastname: Fujii
authors.forename: J
authors.initials: J
authors.lastname: Hirose
authors.forename: M
authors.initials: M
authors.lastname: Harada
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C100152:dipeptidyl peptidase III; D015032:Zinc