title: Identification of zymogen E in a complex with bovine procarboxypeptidase A.
abstract: The presence of zymogen E in bovine pancreatic secretion was demonstrated by activation with trypsin and isolation of protease E. The enzyme, pI = 4.85, has k3 and Km values of 48 s-1 and 4.4 mM, respectively, for acetyl-tri-L-alanine methyl ester and an amino acid composition similar to that of porcine protease E. Gel filtration of the proteins in the secretion provided evidence that bovine zymogen E forms complexes with procarboxypeptidase A, including a ternary complex of these two proteins with chymotrypsinogen C. Taken together with previous observations on porcine zymogen E (Kobayashi, R., Kobayashi, Y., and Hirs, C. H. W. (1978) J. Biol. Chem. 253, 5526-5530) the data suggest that complex formation between procarboxypeptidase A and zymogen E may be a more widespread property of these proteins. The fact that zymogen E occurs as a major constituent in bovine pancreatic secretion in a physiological context n which no requirement for elastolysis exists suggests further that the functional significance of protease E in the digestion of proteins is general and not specific for elastin.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002268:Carboxypeptidases / Q000302:isolation & purification* / Q000378:metabolism; D043422:Carboxypeptidases A; D002417:Cattle; D010450:Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D004789:Enzyme Activation; D007700:Kinetics; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000378:metabolism; D010179:Pancreas / Q000201:enzymology*; D012697:Serine Endopeptidases
chemical_list: D000596:Amino Acids; D009097:Multienzyme Complexes; D002268:Carboxypeptidases; D010450:Endopeptidases; D043422:Carboxypeptidases A; D012697:Serine Endopeptidases; C028736:zymogen E