FXIIa

FXIIa, also known as coagulation factor XIIa or Hageman factor, is a serine protease and a crucial component of the intrinsic pathway of the coagulation cascade. It is synthesized in the liver as an inactive zymogen, factor XII. Activation of factor XII to FXIIa can occur through contact with negatively charged surfaces, such as damaged blood vessel walls, collagen, or certain laboratory glass surfaces.

Once activated, FXIIa initiates a cascade of enzymatic reactions that ultimately leads to the formation of thrombin, an enzyme that converts fibrinogen into fibrin, the main structural component of blood clots. FXIIa's role extends beyond just coagulation; it is also involved in the activation of prekallikrein to kallikrein, which in turn can activate more factor XII, amplifying the process. This kallikrein-kinin system activation contributes to inflammation and blood pressure regulation.

While essential for hemostasis, dysregulation of FXIIa activity has been implicated in thrombotic disorders and inflammatory conditions. Research is ongoing to understand the precise mechanisms by which FXIIa contributes to these pathologies and to explore potential therapeutic targets that modulate its activity for the treatment of various diseases.