MODE OF ACTIVATION AND N-TERMINAL SEQUENCE OF SUBUNIT 2 IN BOVINE PROCARBOXYPEPTIDASE A AND OF PORCINE CHYMOTRYPSINOGEN C

In accordance with what is observed for bovine or porcine chymotrypsinogens A and B, the activation of porcine chymotrypsinogen C and of Subunit II in bovine procarboxypeptidase A involves the specific cleavage by trypsin of the first basic bond in the N-terminal region. The short chain thus formed contains 13 residues instead of 15. The two missing residues correspond to an apparently characteristic deletion at positions 12 and 13. A comparison of the chains (N-terminal sequences) in six zymogens supports the view that bovine Subunit II is a chymotrypsinogen resembling more chymotrypsinogen C than chymotrypsinogens A and B. This suggests the existence in bovine and porcine pancreas of at least two related but distinct chymotrypsinogen lines. © 1969.