眼镜蛇毒蛋白酶natrahagin水解纤维蛋白原的特性及对人血小板聚集的影响(英文)

Fibrinogenolytic properties of natrahagin ( a proteinase from cobra venom) and its effect on human platelet aggregation

目的:研究natrahagin水解纤维蛋白原的特性及其对血小板聚集的影响。方法:SDS-PAGE,水解纤维蛋白原活性测定,血小板聚集实验。结果:Natrahagin与纤维蛋白原以1:50(w/w)孵育,5min内A_α-链几乎完全降解,γ-链的完全降解则至少需6h;其水解可凝固纤维蛋白原的活性为0.349±0.044g·min^(-1)·g^(-1)。Natrahagin浓度依赖性地抑制利托菌素对富血小板血浆和凝血酶(80U·L^(-1))对洗涤血小板的聚集反应,IC_(50)(95％可信限)分别为56(40-79)和3.3(1.4-8.0)mg·L^(-1)。但即使natrahagin达200mg·L^(-1),对ADP和胶原诱导的血小板聚集仍无抑制作用。结论:Natrahagin是一种α,γ-纤维蛋白原溶解酶,可选择性抑制血小板膜糖蛋白Ib介导的血小板聚集。

AIM: To study the fibrinogenolytic properties of natrahagin and its effect on platelet aggregation. METHOD: SDS-PAGE, fibrinogenolytic activity assay, platelet aggregation. RESULTS: Upon incubation of flbrinogen with natrahagin at the ratio of 50: 1 (w/w), Aα-chains of fibrinogen were almost completely hydrolyzed in 5 min; however, at least 6 h was needed for the complete degradation of γ-chains. Fibrinogenolytic activity of natrahagin was 0.349 ±0.044 g·min-1·g-1 as determined by its ability to reduce the clottable fibrinogen. On the other hand, natrahagin concentration-dependency inhibited platelet aggregation induced by ristocetin in platelet-rich plasma and thrombin (80 U·L-1) in washed platelets with IC50 (95 % confidence limit) of 56 (40-79) and 3.3 (1.4 -8.0) mg·L-1. No inhibitory effect was found on collagen- and ADP-induced platelet aggregation even when the dose of natrahagin reached 200 mg · L-1. CONCLUSION: Natrahagin is an α, γ-fibrinogenase with an inhibitory effect on platelet membrane glycoprotein Ib (GPIb)-dependent platelet aggregation.