An inhibitor selective for collagen-stimulated platelet aggregation from the salivary glands of hard tick Haemaphysalis longicornis and its mechanism of action
An inhibitor selective for collagen-stimulated platelet aggregation from the salivary glands of hard tick Haemaphysalis longicornis and its mechanism of action
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DOI：
10.1007/bf02881768
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发表时间：
1999-10-01
期刊：
影响因子：
--
通讯作者：
Li, DC
中科院分区：
文献类型：
--
作者：
Cheng, YG;Wu, HY;Li, DC
长角血蜱唾液腺的可溶性物质被发现可以抑制胶原蛋白、ADP 和凝血酶刺激的血小板聚集。通过凝胶过滤、离子交换和 C-g 反相 HPLC 的组合，将一种抑制成分纯化至唾液腺均质。纯化的活性物质命名为长角蛋白，在还原和非还原条件下的 SDS-PAGE 上显示，其是分子量为 16 000 的蛋白质。血浆中胶原介导的血小板聚集和洗涤后的血小板（IC50 约为 60 nmol/L）被抑制，具有相同的功效。没有观察到其他效应物（包括 ADP、花生四烯酸、凝血酶、瑞斯托菌素、钙离子载体 A23187、血栓素 A2 模拟物 U46619 和 12-O-佛波醇-13-肉豆蔻酸酯乙酸酯）刺激的聚集抑制。 Longiconin 对血小板与胶原蛋白的粘附没有影响。不仅血小板聚集，而且释放反应，以及血小板响应胶原蛋白而增加的细胞内Ca2+水平被长角素完全消除。越来越多的胶原蛋白能够克服长角蛋白对聚集的抑制，表明长角蛋白可能与胶原蛋白具有共同的受体。此外，与异氰酸酯缀合的长角素一起孵育后，胶原纤维没有发出荧光，表明长角素没有直接与胶原纤维结合。长角素的鉴定和分离证明了一种新型血小板抑制剂的存在，它应该有助于更好地理解胶原蛋白刺激血小板的机制。
Soluble materials of salivary glands from Haemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C-g reverse phase HPLC. The purified activity, named longicornin, is a protein of molecular weight 16 000 on SDS-PAGE under both reduced and nonreduced conditions. Collagen-mediated aggregation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effecters, including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol- 13-myristate acetate, was observed. Longiconin had no effect on platelet adhension to collagen. Not only platelet aggregation but also release reaction, and increase of intracellar Ca2+ level of platelets in response to collagen were completely eliminated by longicornin. Increasing amounts of collagen are able to overcome the inhibition of aggregation by longicornin, indicating that longicornin probably shares with collagen a common receptor. In addition, collagen fibers did not emit fluorescence after incubation with isothocyanate-conjugated longicornin, indicating that longicornin did not bind directly to collagen fibers. The identification and isolation of longicornin demonstrates the existence of a new type of platelet inhibitor that should be useful to better understand the mechanism of collagen stimulation of platelets.