China Heparin Injection Grade CAS 9005-49-6

The anticoagulation action of heparin depends on the presence of a specific serine protease inhibitor (serpin) of thrombin, antithrombin III, in normal blood.
Heparin binds to antithrombin III and induces a conformational change that accelerates the interaction of antithrombin III with the coagulation factors. Heparin also catalyzes the inhibition of thrombin by heparin cofactor II, a circulating inhibitor. Smaller amounts of heparin are needed to prevent the formation of free thrombin than are needed to inhibit the protease activity of clot-bound thrombin. Inhibition of free thrombin is the basis of low-dose prophylactic therapy.