Thrombin is a protease (34 kD) generated in blood clotting that acts on fibrinogen to produce fibrin. It consists of two chains: A and B chains that are linked by a disulphide bond. B chain has sequence homology with pancreatic serine proteases.
Thrombin is produced from prothrombin by the action either of the extrinsic system (tissue factor _ phospholipid) or, more importantly, the intrinsic system (contact of blood with a foreign surface or connective tissue). Both extrinsic and intrinsic systems activate plasma factor X to form factor Xa, which, then, in conjunction with phospholipid (tissue derived or platelet factor 3) and factor V, catalyses the conversion. In humans, it is encoded by the F2 gene.
- activated blood-coagulation factor II
- (blood) coagulation factor IIa
- (blood) clotting factor IIa
- factor IIa
- E thrombin