Coagulation factor X (Factor Xa) (FXa)

Coagulation factor X (Factor Xa) is a pivotal serine protease located at the convergence of the intrinsic and extrinsic pathways of the blood coagulation cascade [1]. Its primary biological role is to catalyze the conversion of prothrombin into thrombin within the prothrombinase complex, a critical step for fibrin formation and the stabilization of blood clots [1][4]. The target mechanism described as Factor Xa via antithrombin refers to the indirect inhibition of this enzyme mediated by the endogenous plasma protein antithrombin III (ATIII) [2][5]. Pharmacological agents such as fondaparinux and low-molecular-weight heparins (LMWHs) bind to a specific pentasaccharide sequence on ATIII, inducing a conformational change that dramatically accelerates its natural ability to neutralize Factor Xa [3][5]. This mechanism is a cornerstone of anticoagulant therapy, used extensively to prevent and treat thromboembolic disorders like deep vein thrombosis and pulmonary embolism while minimizing direct interference with thrombin activity [3][4].

Other names

Stuart-Prower factorThrombokinaseProthrombinaseFactor 10F10Antithrombin-dependent Factor Xa inhibitor target

Indirect inhibition of Factor Xa through the allosteric activation of Antithrombin III (ATIII). Drugs bind to ATIII, inducing a conformational change that increases its affinity for Factor Xa by approximately 1,000-fold [3][5].