Coagulation factor Xa and thrombin (serine proteases of coagulation) (Factor Xa (FXa), Thrombin (FIIa))

Coagulation factor Xa and thrombin are central serine protease enzymes in the blood coagulation cascade. Factor Xa cleaves prothrombin to generate thrombin (activated Factor II), which then converts fibrinogen to fibrin, resulting in clot formation. These proteases possess a characteristic serine protease catalytic triad and are regulated by endogenous inhibitors (serpins) and several anticoagulant drug classes. They are tightly controlled to prevent both thrombosis and excessive bleeding. Beyond coagulation, these enzymes contribute to inflammatory signaling, vascular biology, and tissue repair. Pharmacological inhibition of factor Xa and thrombin is a mainstay for the prevention and treatment of arterial and venous thrombotic disorders.

Other names

Thrombin: Prothrombinase, Factor IIa, FIIaFactor Xa: FXa, Activated factor X, Stuart-Prower factorGeneral class: Coagulation serine proteases, Clotting factor serine proteases, Haemostatic serine proteases, Blood coagulation factors

Direct enzymatic inhibition (bind active site or exosites). Indirect inhibition (promote inactivation by antithrombin, e.g., heparin). Inhibition of factor synthesis (vitamin K antagonists block carboxylation of factors, rendering them inactive).