Identification and characterization of novel salivary thrombin inhibitors from the ixodidae tick, Haemaphysalis longicornis
Identification and characterization of novel salivary thrombin inhibitors from the ixodidae tick, Haemaphysalis longicornis
复制标题
DOI：
10.1046/j.1432-1033.2003.03560.x
复制
发表时间：
2003-05-01
期刊：
影响因子：
--
通讯作者：
Chinzei, Y
中科院分区：
文献类型：
--
作者：
Iwanaga, S;Okada, M;Chinzei, Y
新的抗凝血酶分子被确定从硬蜱科蜱，长角血蜱。这些分子被命名为madanin 1和2，是7 kDa的蛋白质，与以前鉴定的任何蛋白质都没有显着的相似性。使用人血浆的分析表明，madanin 1和2剂量依赖性延长活化部分凝血活酶时间和凝血酶原时间，表明它们抑制内源性和外源性途径。表面等离子体共振直接结合实验表明，madanin 1和2特异性地与凝血酶相互作用。此外，它清楚地表明，madanin 1和2抑制纤维蛋白原转化为纤维蛋白的凝血酶，凝血酶催化的活化因子V和因子VIII，凝血酶诱导的血小板聚集，而不影响凝血酶酰胺水解活性。这些结果表明，马达宁1和2结合到凝血酶分子上的阴离子结合外位点1，但不结合到活性裂缝，并干扰纤维蛋白原，因子V，因子VIII和血小板上的凝血酶受体与阴离子结合外位点1的关联。它们似乎是外来位点1定向的竞争性抑制剂。
Novel antithrombin molecules were identified from the ixodidae tick, Haemaphysalis longicornis . These molecules, named madanin 1 and 2, are 7-kDa proteins and show no significant similarities to any previously identified proteins. Assays using human plasma showed that madanin 1 and 2 dose-dependently prolonged both activated partial thromboplastin time and prothrombin time, indicating that they inhibit both the intrinsic and extrinsic pathways. Direct binding assay by surface plasmon resonance measurement demonstrated that madanin 1 and 2 specifically interacted with thrombin. Furthermore, it was clearly shown that madanin 1 and 2 inhibited conversion of fibrinogen into fibrin by thrombin, thrombin-catalyzed activation of factor V and factor VIII, and thrombin-induced aggregation of platelets without affecting thrombin amidolytic activity. These results suggest that madanin 1 and 2 bind to the anion-binding exosite 1 on the thrombin molecule, but not to the active cleft, and interfere with the association of fibrinogen, factor V, factor VIII and thrombin receptor on platelets with an anion-binding exosite 1. They appear to be exosite 1-directed competitive inhibitors.