Intrinsic tenase complex (Intrinsic tenase)

The intrinsic tenase complex is a multi-component enzymatic assembly that plays a central role in the propagation phase of the blood coagulation cascade. It is composed of the serine protease Factor IXa, the non-enzymatic cofactor Factor VIIIa, and the substrate Factor X, all of which assemble on an anionic phospholipid membrane surface (typically provided by activated platelets) in the presence of calcium ions (Mann et al., 1990, PMID: 2115815). The primary biological function of this complex is to catalyze the conversion of Factor X to Factor Xa, a step that is essential for the subsequent burst of thrombin generation required for stable clot formation. In patients with Hemophilia A, the absence or dysfunction of Factor VIII prevents the formation of this complex, leading to impaired hemostasis and a high risk of spontaneous bleeding. Therapeutic agents such as the bispecific antibody Emicizumab (Hemlibra) target this assembly by physically bridging Factor IXa and Factor X, thereby mimicking the scaffolding function of Factor VIIIa and restoring the enzymatic efficiency of the tenase complex (FDA Hemlibra Label; Lenting et al., 2017, PMID: 28835441). This target is critical for modern hemophilia management and is a focus for developing next-generation bypassing agents and anticoagulants.

Other names

Coagulation factor IXa / factor X / anionic phospholipid membrane complexFactor IXa-Factor X complexFIXa-FVIIIa-FX complexTenase complex

Bispecific antibody-mediated bridging of Factor IXa and Factor X to facilitate the proteolytic activation of Factor X to Factor Xa, mimicking the function of activated Factor VIII.