title: The isolation and partial characterization of precursor forms of ostrich carboxypeptidase.
abstract: Ostrich carboxypeptidases A and B were recently purified and characterized. The aim of this study was to isolate and purify, and partially characterize in terms of molecular weight, pI, amino acid composition and N-terminal sequencing, the precursor forms of carboxypeptidases from the ostrich pancreas. Inhibition studies with soybean trypsin inhibitor and activation studies with three proteases (bovine trypsin, bovine chymotrypsin and porcine elastase) were performed on crude ostrich acetone powder and the carboxypeptidase A and B activities were determined. SDS-PAGE was carried out after every incubation to monitor the rate and degree of conversion of a M(r) 66K component to procarboxypeptidase and carboxypeptidase A and B. The precursor forms were purified by Toyopearl Super Q and Pharmacia Mono Q chromatography. All three proteases converted the M(r) 66K component to procarboxypeptidases and carboxypeptidases over a set time interval, with carboxypeptidase A and B activities being detected in the acetone powder. Chymotrypsin was the preferred protease since it exhibited a more controlled activation of the procarboxypeptidases. The amino acid composition of procarboxypeptidase A revealed 525 residues. The N-terminal sequence of procarboxypeptidase A showed considerable homology when compared with several other mammalian sequences. M(r) and pI values of 52K and 5.23 were obtained for procarboxypeptidase A, respectively. This study indicated that ostrich procarboxypeptidase A is closely related to other mammalian procarboxypeptidase A molecules in terms of physicochemical properties.
authors.affiliation: Department of Biochemistry and Microbiology, University of Port Elizabeth, South Africa.
authors.forename: N T
authors.initials: NT
authors.lastname: Mkwetshana
authors.forename: R J
authors.initials: RJ
authors.lastname: Naudé
authors.forename: W
authors.initials: W
authors.lastname: Oelofsen
authors.forename: T
authors.initials: T
authors.lastname: Naganuma
authors.forename: K
authors.initials: K
authors.lastname: Muramoto
mesh_terms: D000096:Acetone / Q000737:chemistry; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D043422:Carboxypeptidases A; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods; D002918:Chymotrypsin / Q000378:metabolism; D002919:Chymotrypsinogen / Q000378:metabolism; D004284:Dogfish; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010179:Pancreas / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D013045:Species Specificity; D020310:Struthioniformes
chemical_list: D000596:Amino Acids; D004792:Enzyme Precursors; C096020:chymotrypsinogen C; D000096:Acetone; D002919:Chymotrypsinogen; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D043424:Carboxypeptidase B; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D010196:Pancreatic Elastase