长白白眉蝮蛇类凝血酶的研究Ⅱ——理化、酶学性质的鉴定

THE CHARACTERIZATION OF A THROMBIN-LIKE ENZYME FROM VENOM OF AGKISTRODON HALYS USSURIENSIS EMELINOV

长白白眉蝮蛇类凝血酶分子量为39 000,是一种糖蛋白。氨基酸组成分析表明,此酶共含303个氨基酸残基,其中酸性氨基酸含量较高,等电点为4.25。该酶对BAEE(苯甲酰-L-精氨酸乙酯)水解活力的最适pH值为8左右,Km为3.53×10^(-4)mol/L,其活性可被DFP(二异丙基氟磷酸)及PMSF(苯甲基磺酰氟)所抑制。催化降解纤维蛋白原过程中,只释放纤肽A,不释放纤肽B,形成的纤维蛋白可被5 mol/L尿素液溶解。

Our observations showed that thrombin-like enzyme from the snake venomwas a glycoprotein with molecular weight of about 39 000, containing approxi-mately 303 amino acid residues. pl of the enzyme is 4.25. The thrombin-likeenzyme hydrolyzes BAEE (Km=3.53×10^(-4)) with an optimum pH of 8.0.The esterase activity of the enzyme can be inhibited by DFP or PMSF. Ithas been confirmed by HPLC that unlike thrombin which releases fibrinopeptidesA and B from fibrinogen in the formation of fibrin, the thrombin-like enzymehas no effect on the B chain of fibrinogen.