α2-antiplasmin

the most important inhibitor of fibrinolysis, an α₂-globulin, M_r 53,000, found in large quantities in normal blood; it is synthesized predominantly in the liver and functions by forming stable complexes with free plasmin. It is also cross-linked to fibrin by the action of coagulation factor XIII and inhibits the binding of plasminogen to fibrin. Deficiency of this protein, an autosomal recessive trait, is associated with severe bleeding, including hemarthrosis.