title: Dissociation of bovine 6S procarboxypeptidase A by reversible condensation with 2,3-dimethyl maleic anhydride: application to the partial characterization of subunit III.
abstract: Bovine 6S procarboxypeptidase A can be dissociated into its three subunits by acylation with dimethyl maleic anhydride. The deacylated subunits are obtained in a largely native form due to instability of the bonds to dimethyl maleate at pH values near neutrality. The seven first residues of subunit III are identical to residues 18-24 of bovine chymotrypsinogen B and very similar with the same residues in bovine chymotrypsinogen A and C (subunit II) and also in proelastase A of the African lungfish. Therefore, this subunit is likely to be a chymotrypsinogen or proelastase-A-like zymogen which has lost the ability to be activated on account of a deletion of the N-terminal residues from half-cystine 1 to valine 17. Like other pancreatic zymogens, subunit III appears to possess a weakly functional active site.
mesh_terms: D000215:Acylation; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000812:Anhydrides; D000818:Animals; D002268:Carboxypeptidases / Q000032:analysis; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D010450:Endopeptidases; D004792:Enzyme Precursors / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008298:Maleates; D008299:Maleic Anhydrides; D010179:Pancreas / Q000201:enzymology*; D010455:Peptides / Q000032:analysis / Q000302:isolation & purification
chemical_list: D000596:Amino Acids; D000812:Anhydrides; D004792:Enzyme Precursors; D046911:Macromolecular Substances; D008298:Maleates; D008299:Maleic Anhydrides; D010455:Peptides; C007474:2,3-dimethylmaleic anhydride; D002268:Carboxypeptidases; D010450:Endopeptidases