Hageman - Factor - Dependent Fibrinolysis : Generation of Fibrinolytic Activity by the Interaction of Human Activated Factor

Human coagulation factor XI has been purified, and upon activation with Hageman factor fragments. was found to convert the fibrinolytic proenzyme plasminogen to plasmin. This proactivator activity was shown to be functionally and antigenically distinct from prekallikrein. When the gamma-globulin fractions of plasma deficient in Hageman factor, prekallikrein and factor Xl were isolated, factor-Xl-deficient plasma possessed two-thirds of the plasminogen proactivator activity of the Hageman-factor-deficient plasma, while prekalIikrein deficient plasma had only one-third of the plasminogen proactivator activity. Thus, the Hageman-factor-dependent plasminogen proactivator previously reported to be present in the gamma-globulin fraction of normal human plasma is a function of prekallikrein and factor Xl. while the activity observed in prekallikrein-deficient plasma is attributable to factor XI. When compared utilizing digestion of iodinated fibrin. prekallikrein and factor Xla had similar potency per active site; they were, however, far less active than urokinase.