Procoagulant subsystem

Plasma Coagulation Factors - Procoagulant Subsystem Components ... 

The first and most completely characterized of the activation complexes of the procoagulant subsystem is that of prothrombin activation. Because of this, the prothrombin activation complex will be described in greater detail than the other, similar activation complexes (Figure 36-9) The general principles described below apply to all of the complexes. 

Because inactivation of factors Va and Villa by activated protein C promotes the dissociation of the pro-teinases, cofactor protein inactivation complements the action of the proteinase inhibitors. This eliminates the protection that the proteinases have when bound to their cofactor proteins and substrates. Inactivation of proteinases by SERPINS occurs via a common mechanism that involves a Michaelis complex between the proteinase and the inhibitor (Figure 36-16). This mechanism applies to all serine proteinases of the hemostatic system, i.e., the procoagulant, anticoagulant, and fibrinolytic subsystem proteinases. 

---