Macromolecular specificity determinants on thrombin for fibrinogen and thrombomodulin.
Macromolecular specificity determinants on thrombin for fibrinogen and thrombomodulin.
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DOI：
10.1016/s0021-9258(18)60437-5
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发表时间：
1989-07
期刊：
影响因子：
--
通讯作者：
H. Jakubowski;W. Owen
中科院分区：
文献类型：
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作者：
H. Jakubowski;W. Owen
内皮细胞表面膜蛋白凝血调节蛋白与凝血酶高亲和力结合，作为蛋白C活化的辅助因子和纤维蛋白原水解的抑制剂。我们以前已经表明，牛凝血调节蛋白是纤维蛋白原与凝血酶结合的竞争性抑制剂，但对凝血酶对三肽底物或抗凝血酶III的活性没有影响。因此，凝血调节蛋白和纤维蛋白原可能共享凝血酶上不同于活性位点的大分子特异性位点。在这项研究中，我们研究了凝血酶-血栓调节蛋白与纤维蛋白原和各种凝血酶衍生物的相互作用。我们发现纤维蛋白原是血栓调节蛋白与凝血酶结合的竞争性抑制剂，其aKis= 10µM。凝血酶衍生物（牛（磷酸吡哆醛）4-凝血酶和人凝血酶Quick I）与纤维蛋白原结合的亲和力大大降低，与凝血调节蛋白相互作用的亲和力也大大降低。这些结果与血栓调节蛋白和纤维蛋白原在凝血酶上共享大分子特异性位点的假设是一致的。
The endothelial cell surface membrane protein thrombomodulin binds thrombin with high affinity and acts as both a cofactor for protein C activation and an inhibitor of fibrinogen hydrolysis. We have previously shown that bovine thrombomodulin is a competitive inhibitor of fibrinogen binding to thrombin but has no effect on thrombin activity toward tripeptide substrates or antithrombin III. Hence, thrombomodulin and fibrinogen may share macromolecular specificity sites on thrombin which are distinct from the active site. In this investigation, we have studied the interaction of thrombin-thrombomodulin with fibrinogen and various thrombin derivatives. We show that fibrinogen is a competitive inhibitor of thrombomodulin binding to thrombin, with aKis= 10 µM. Thrombin derivatives (bovine (pyridoxal phosphate)4-thrombin and human thrombin Quick I), which bind fibrinogen with much reduced affinity, are shown to also interact with thrombomodulin with greatly reduced affinity. These results are consistent with the hypothesis that thrombomodulin and fibrinogen share macromolecular specificity sites on thrombin.