Zhang Y, Gao R, Lee W H, Zhu S W, Xiong Y L, Wang W Y
Department of Animal Toxinology, Kunming Institute of Zoology, Chinese Academy of Sciences, Yunnan, P.R. China.
Toxicon. 1998 Jan;36(1):131-42. doi: 10.1016/s0041-0101(97)00050-0.
Trimeresurus stejnegeri venom which contains TSV-PA (a specific plasminogen activator sharing 60-70% sequence homology with venom fibrinogen-clotting enzymes), also possesses fibrinogen-clotting activity in vitro. A fibrinogen-clotting enzyme (stejnobin) has been purified to homogeneity by gel filtration and ion-exchange chromatography on a Mono-Q column. It is a single-chain glycoprotein with a mol. wt of 44,000. The NH2-terminal amino acid sequence of stejnobin shows great homology with venom fibrinogen-clotting enzymes and TSV-PA. Like TSV-PA, stejnobin was able to hydrolyse several chromogenic substrates. Comparative study of substrate specificities of stejnobin and other venom proteases purified in our laboratory was carried out on five chromogenic substrates. Stejnobin clotted human fibrinogen with a specific activity of 122 NIH thrombin-equivalent units/mg protein. However, stejnobin did not act on other blood coagulation factors, such as factor X, prothrombin and plasminogen. Diisopropyl fluorophosphate and phenylmethanesulfonyl fluoride inhibited its activity, whereas ethylenediamine tetracetic acid had no effect on it, indicating that it is a serine protease. Although stejnobin showed strong immunological cross-reaction with polyclonal antibodies raised against TSV-PA, it was interesting to observe that, unlike the case of TSV-PA, these antibodies did not inhibit the amidolytic and fibrinogen-clotting activities of stejnobin.
竹叶青蛇毒含有TSV-PA（一种与蛇毒纤维蛋白原凝血酶具有60-70%序列同源性的特异性纤溶酶原激活剂），在体外也具有纤维蛋白原凝血活性。一种纤维蛋白原凝血酶（竹叶青蛋白酶）已通过凝胶过滤和在Mono-Q柱上的离子交换色谱法纯化至同质。它是一种单链糖蛋白，分子量为44,000。竹叶青蛋白酶的NH2末端氨基酸序列与蛇毒纤维蛋白原凝血酶和TSV-PA具有高度同源性。与TSV-PA一样，竹叶青蛋白酶能够水解几种显色底物。在五种显色底物上对竹叶青蛋白酶和我们实验室纯化的其他蛇毒蛋白酶的底物特异性进行了比较研究。竹叶青蛋白酶使人类纤维蛋白原凝结，比活性为122 NIH凝血酶当量单位/毫克蛋白质。然而，竹叶青蛋白酶对其他凝血因子，如因子X、凝血酶原和纤溶酶原没有作用。二异丙基氟磷酸酯和苯甲基磺酰氟抑制其活性，而乙二胺四乙酸对其没有影响，表明它是一种丝氨酸蛋白酶。尽管竹叶青蛋白酶与针对TSV-PA产生的多克隆抗体表现出强烈的免疫交叉反应，但有趣的是观察到，与TSV-PA的情况不同，这些抗体并不抑制竹叶青蛋白酶的酰胺水解和纤维蛋白原凝血活性。
