Synergistic effect of aptamers that inhibit exosites 1 and 2 on thrombin
Synergistic effect of aptamers that inhibit exosites 1 and 2 on thrombin
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DOI：
10.1261/rna.1240109
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发表时间：
2009-12-01
期刊：
影响因子：
4.5
通讯作者：
Sullenger, Bruce A.
中科院分区：
文献类型：
--
作者：
Nimjee, Shahid M.;Oney, Sabah;Sullenger, Bruce A.
凝血酶是一种多功能蛋白酶，在止血、血栓形成和炎症中起关键作用。大多数凝血酶抑制剂目前用作抗血栓药物靶向凝血酶的活性位点，并抑制其所有的无数的活性。外源位点1和2是凝血酶表面上不同的区域，通过介导与底物、受体和辅因子的结合，为凝血酶的蛋白水解活性提供特异性。外源位点1介导纤维蛋白原、蛋白水解激活受体和一些凝血因子的结合和裂解，而外源位点2介导肝素和血小板受体GPIb-IX-V的结合。两种与凝血酶结合的核酸配体的晶体结构已被解决。此前，Padmanabhan和他的同事们解决了与外源位点1结合的DNA适体的结构，我们报道了与凝血酶上的外源位点2结合的RNA适体的结构。基于这些结构研究，我们推测这两个适体不会竞争与凝血酶的结合。我们观察到，同时用适体阻断两种外源位点导致凝血酶依赖性血小板活化和促凝活性的协同抑制。这种外源性1和外源性2抑制剂的组合可能提供一种特别有效的抗血栓方法。
Thrombin is a multifunctional protease that plays a key role in hemostasis, thrombosis, and inflammation. Most thrombin inhibitors currently used as antithrombotic agents target thrombin's active site and inhibit all of its myriad of activities. Exosites 1 and 2 are distinct regions on the surface of thrombin that provide specificity to its proteolytic activity by mediating binding to substrates, receptors, and cofactors. Exosite 1 mediates binding and cleavage of fibrinogen, proteolytically activated receptors, and some coagulation factors, while exosite 2 mediates binding to heparin and to platelet receptor GPIb-IX-V. The crystal structures of two nucleic acid ligands bound to thrombin have been solved. Previously Padmanabhan and colleagues solved the structure of a DNA aptamer bound to exosite 1 and we reported the structure of an RNA aptamer bound to exosite 2 on thrombin. Based upon these structural studies we speculated that the two aptamers would not compete for binding to thrombin. We observe that simultaneously blocking both exosites with the aptamers leads to synergistic inhibition of thrombin-dependent platelet activation and procoagulant activity. This combination of exosite 1 and exosite 2 inhibitors may provide a particularly effective antithrombotic approach.