EFFECTS OF ALPHA(2)-PLASMIN INHIBITOR ON PLASMINOGEN ACTIVATION BY STAPHYLOKINASE PLASMINOGEN COMPLEX

Using a stable cross-linked SAK/plg complex, the effects of alpha(2)-p lasmin inhibitor on plasminogen activation by SAK were investigated. a lpha(2)-Plasmin inhibitor inhibited dose-dependently plasminogen activ ation by the SAK/plg complex. When FCB-2 or EACA was added to the reac tion mixture of SAK/plg complex and alpha(2)-plasmin inhibitor, the in hibitory activity of alpha(2)-plasmin inhibitor was abolished and the enzymatic activity of the complexes was restored. alpha(2)-Plasmin inh ibitor inhibited the activity of the SK/plg complex, but neither FCB-2 nor EACA restored the plasminogen activator activity in the mixture o f SK/plg complex and alpha(2)-plasmin inhibitor. Using I-125-labeled S AK/plg complex with alpha(2)-plasmin inhibitor was analyzed. The SAK/p lg complex produced a new complex with alpha(2)-plasmin inhibitor. The formation of a new high molecular weight complex with alpha(2)-plasmi n inhibitor was abolished by both EACA or FCB-2. With regard to the SK /plg complex, neither EACA nor FCB-2 suppressed the complex formation with alpha(2)-plasmin inhibitor. These findings indicate that the SAK/ plg complex binds to fibrin, that this complex expresses plasminogen a ctivator activity without being affected by alpha(2)-plasmin inhibitor .