This protein belongs to a family of Zn-containing metallocarboxypeptidases specific to C-terminal lysine and arginine residues. It circulates in plasma as a zymogen with molecular weight of 55 kDa (401 amino acid residues; pI 5.0). Being activated by thrombin-thrombomodulin complex during blood coagulation, it exerts carboxypeptidase activity. Activated carboxypeptidase B2 removes C-terminal lysine residues from fibrin, which is necessary for plasminogen binding to fibrin. This prevents plasminogen from activation into plasmin and retards the lysis of a fibrin clot. The concentration in plasma of healthy people is 5-10 ug/ml. High plasma levels were found in patients with stable angina pectoris and angiographically verified coronary artery disease. Elevated concentration in blood is considered as a risk factor for venous thrombosis. A deficiency might contribute to the severity of bleeding disorders in hemophilias A and B, and decreased levels are found in chronic liver disease.