PANCREATIC PROCARBOXYPEPTIDASES - OLIGOMERIC STRUCTURES AND ACTIVATION PROCESSES REVISITED

The activation peptides of procarboxypeptidases of the A1 type act in a post-activation mechanism of control, limiting the expression of act ivity immediately after the limited proteolysis has occurred. This eff ect is due to structural complementarity between the enzymatic moiety and the released fragments, and is further enhanced by the occurrence of procarboxypeptidase A1 in oligomeric complexes of different type de pending on the species studied. In those complexes, the activation seg ment has an important role in the stabilisation of the quaternary stru cture. The relationship between oligomeric structure and activation is reviewed here for two of the most extensively studied systems.