title: Further characterization of subunit III of bovine procarboxypeptidase A-S6 as a non activatable zymogen.
abstract: The homology of Subunit III of bovine procarboxypeptidase A-S6 (EC 3.4.12.-) with Subunit II (bovine chymotrypsinogen C) of the same complex, already reported in a previous publication (Puigserver, A. and Desnuelle, P. (1975) Proc. Natl. Acad. Sci. U.S. 72, 2442-2445) has been extended to the position of the single methionine of the chains. The sequence linked by 4 disulfide bridges out of 5 are also probably homologous in the 2 proteins. The last bridge is displaced in Subunit III as a consequence of the deletion of the N-terminal half-cystine. Subunit II, which is not activatable by trypsin, due to the loss of essential residues in the N-terminal region, has conserved a weakly functional active site reacting with concentrated diisopropylfluorophosphate at exactly the same rate as that of Subunit II.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002268:Carboxypeptidases / Q000302:isolation & purification / Q000378:metabolism; D002417:Cattle; D002919:Chymotrypsinogen / Q000378:metabolism; D004220:Disulfides / Q000032:analysis; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000302:isolation & purification / Q000378:metabolism; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D014357:Trypsin
chemical_list: D000596:Amino Acids; D004220:Disulfides; D004792:Enzyme Precursors; D046911:Macromolecular Substances; D010446:Peptide Fragments; D002919:Chymotrypsinogen; D002268:Carboxypeptidases; D014357:Trypsin