text: Some, but not all, carboxypeptidases are initially produced in an inactive form; this precursor form is referred to as a procarboxypeptidase.  In the case of pancreatic carboxypeptidase A, the inactive zymogen form - pro-carboxypeptidase A - is converted to its active form - carboxypeptidase A - by the enzyme trypsin.  This mechanism ensures that the cells wherein pro-carboxypeptidase A is produced are not themselves digested.