Thrombin

Thrombin (Thr) is a serine protease. Prothrombin (PThr) is cleaved to form Thr in the coagulation cascade. Thr catalyzes the conversion of fibrinogen to the insoluble fibrin. Thr is comnposed of heavy chain (HC) and light chain (LC). Prethrombin-1 lacks 155 N-terminal residues of PThr and is composed of a single polypeptide chain. Prethrombin-2 is the product of proteolysis of prethrombin-1 by trypsin or by active factor X. P-PACK Thr is a chemicaly modified Thr with inactivated catalytic site and active anion binding site. Hirudin is the most potent natural inhibitor of Thr.