Glu-plasminogen I and II: their activation by urokinase and streptokinase in the presence of fibrin and fibrinogen.

Two isozymes of a native form of human plasminogen (plg), Glu-plg I and II, were isolated. Glu-plg I or II was activated by urokinase (UK) or streptokinase (SK) in the presence of fibrinogen or fibrin. The activation of Glu-plg I was enhanced more than that of Glu-plg II in the presence of fibrin. Fibrin caused better activation of both Glu-plg I and II than fibrinogen. When fibrinolysis or fibrinogenolysis was measured, fibrin was degraded faster than fibrinogen after the activation of Glu-plg I and II by UK. These results suggest that the activation of Glu-plg I was enhanced more than that of Glu-plg II in the presence of fibrin or to less extent fibrinogen.