Interaction Of Plasminogen With Human Platelets

血凝块的溶解（纤溶）需要纤溶酶，一种由组织纤溶酶原激活剂（tPA）激活纤溶酶原而产生的蛋白酶。已知纤溶酶原和tPA都与血小板表面结合，在那里它们的相互作用大大加速。因此，血小板是纤溶的重要促进剂。我们的实验室一直在研究纤溶酶原和血小板的相互作用，通过两种类型的分析：平衡结合实验和血小板依赖性纤溶酶原激活的速率测量。我们发现，用凝血酶刺激血小板可增加纤溶酶原与血小板表面的高亲和力结合，并在血小板存在的情况下大大加快纤溶酶原转化为纤溶酶的速度。用羧肽酶B处理过的血小板，可以去除c端赖氨酸，缺乏高亲和力的纤溶酶原结合，并且支持纤溶酶原转化的能力大大降低。

Dissolution of blood clots (fibrinolysis) requires plasmin, a protease derived from the activation of plasminogen by tissue plasminogen activator (tPA). Both plasminogen and tPA are known to bind to the surface of platelets, where their interaction becomes greatly accelerated. Therefore, platelets are important promoters of fibrinolysis. Our laboratory has been examining the interaction of plasminogen and platelets with two types of assays: equilibrium binding experiments and rate measurements of platelet-dependent plasminogen activation. We have found that stimulation of platelets with thrombin increases high-affinity binding of plasminogen to the platelet surface and greatly accelerates the rate of plasminogen conversion to plasmin in the presence of platelets. Platelets that have been treated with carboxypeptidase B, which removes C-terminal lysines, lack high-affinity plasminogen binding and demonstrate much less ability to support plasminogen conversion.