Peptidase M14 Carboxypeptidase (CP) B2 (CPB2, also known as plasma carboxypeptidase B, carboxypeptidase U, CPU, and thrombin-activable fibrinolysis inhibitor, TAFI; MEROPS identifier M14.009; ), belongs to the carboxpeptidase A/B subfamily of the M14 family of metallocarboxypeptidases (MCPs). The M14 family are zinc-binding CPs which hydrolyze single, C-terminal amino acids from polypeptide chains, and have a recognition site for the free C-terminal carboxyl group, which is a key determinant of specificity.CPB2 enzyme displays B-like activity; it only cleaves the basic residues lysine or arginine. It is produced and secreted by the liver as the inactive precursor, procarboxypeptidase U or PCPB2, commonly referred to as thrombin-activatable fibrinolysis inhibitor (TAFI). It circulates in plasma as a zymogen bound to plasminogen, and the active enzyme, TAFIa, inhibits fibrinolysis. It is highly regulated; increased TAFI concentrations are thought to increase the risk of thrombosis and coronary artery disease by reducing fibrinolytic activity while low TAFI levels have been correlated with chronic liver disease [, , ].
