Jin Yang, Lu Qiu-Min, Wang Wan-Yu, Xiong Yu-Liang
Department of Animal Toxinology, Kunming Institute of Zoology, Kunming 650223, Yunnan, PR China.
Comp Biochem Physiol B Biochem Mol Biol. 2002 Jul;132(3):529-34. doi: 10.1016/s1096-4959(02)00069-6.
Jerdonobin and jerdofibrase are two serine proteases purified from the venom of Trimeresurus jerdonii. The Michaelis constant K(m) and the catalytic rate constant K(cat) of jerdonobin or jerdofibrase on three chromogenic substrates, H-D-Pro-Phe-Arg-pNA (S2302), H-D-Phe-pipecolyl-Arg-pNA (S2238), and H-D-Val-Leu-Lys-pNA (S2251) were obtained from lineweaver-Burk plots. Jerdofibrase could hydrolyze all three substrates, but jerdonobin had no detectable activity on S2251, suggesting a relatively broader substrate specificity for jerdofibrase than jerdonobin. By SDS-PAGE, jerdofibrase preferentially degraded Bbeta-chain of fibrinogen. It also degraded Aalpha-chain of fibrinogen with relatively slow activity, but did not act on the gamma-chain. In contrast, jerdonobin did not degrade fibrinogen within 12 h. Fibrinopeptides liberation test, identified by HPLC, showed jerdonobin released fibrinopeptide A and a small amount of fibrinopeptide B. Unlike jerdonobin, jerdofibrase mainly released fibrinopeptide B. These results indicate that the two enzymes differ in their ability to hydrolyze chromogenic substrates and in their actions on fibrinogen.
竹叶青蛇毒纤溶酶原激活剂和竹叶青蛇毒纤维酶是从竹叶青蛇毒液中纯化得到的两种丝氨酸蛋白酶。通过林-贝氏图获得了竹叶青蛇毒纤溶酶原激活剂或竹叶青蛇毒纤维酶作用于三种生色底物H-D-脯氨酸-苯丙氨酸-精氨酸-对硝基苯胺（S2302）、H-D-苯丙氨酸-哌啶基-精氨酸-对硝基苯胺（S2238）和H-D-缬氨酸-亮氨酸-赖氨酸-对硝基苯胺（S2251）的米氏常数K(m)和催化速率常数K(cat)。竹叶青蛇毒纤维酶能够水解所有这三种底物，但竹叶青蛇毒纤溶酶原激活剂对S2251没有可检测到的活性，这表明竹叶青蛇毒纤维酶的底物特异性比竹叶青蛇毒纤溶酶原激活剂相对更广泛。通过SDS-PAGE分析，竹叶青蛇毒纤维酶优先降解纤维蛋白原的Bβ链。它也以相对较慢的活性降解纤维蛋白原的Aα链，但对γ链没有作用。相比之下，竹叶青蛇毒纤溶酶原激活剂在12小时内不降解纤维蛋白原。通过HPLC鉴定的纤维蛋白肽释放试验表明，竹叶青蛇毒纤溶酶原激活剂释放纤维蛋白肽A和少量纤维蛋白肽B。与竹叶青蛇毒纤溶酶原激活剂不同，竹叶青蛇毒纤维酶主要释放纤维蛋白肽B。这些结果表明这两种酶在水解生色底物的能力以及对纤维蛋白原的作用方面存在差异。
