【摘要】 以苯甲酰－Ｌ－精氨酸乙酯（ｂｅｎｚｏｙｌ－Ｌ－ａｒｇｉｎｉｎｅｅｔｈｙｌｅｓｔｅｒ，ＢＡＥＥ）为底物，研究了蚯蚓体内纤溶酶原激活剂（ｐｌａｓｍｉｎｏｇｅｎａｃｔｉｖａｔｏｒｆｒｏｍＥｉｓｅｎｉａｆｅｔｉｄａ，ｅ－ＰＡ）的酶学性质．酶促反应的最适ｐＨ为８．４，ｅ－ＰＡ降解ＢＡＥＥ的Ｋｍ为１．２４±０．１６×１０－５ｍｏｌ／Ｌ，Ｋｃａｔ为１３．８０±４．０２ｓ－１．测定了构成ｅ－ＰＡ的大，小亚基分别降解ＢＡＥＥ的Ｋｍ和Ｋｃａｔ．结果表明，大亚基的Ｋｍ与全酶的Ｋｍ相差不多，但比小亚基小约１０倍，即对底物的亲和力比小亚基强约一个数量级．大小亚基的Ｋｃａｔ比较接近，分别是全酶的１／６和１／３．研究了８种抑制剂对ｅ－ＰＡ降解ＢＡＥＥ活性的影响，其中ｐｅｐｓｔａｔｉｎ和Ｅ－６４（一种巯基抑制剂）对酶促反应有激活作用，ＴＰＣＫ，ＴＬ－ＣＫ，ＰＭＳＦ，ｃｈｙｍｏｓｔａｔｉｎ和ｌｅｕｐｅｐｔｉｎ对其有不同程度的抑制作用，ＥＤＴＡ对ｅ－ＰＡ的活性没有影响．对ｅ－ＰＡ的ＢＡＥＥ活性和ｅ－ＰＡ的纤溶活性之间作了比较．更多还原

【Abstract】 To detect the enzymology kinetic of ePA(a plasminogen activator from Eisenia fetida),benzoylLarginine ethyl ester(BAEE) was used as substrate.The optimum pH of the degradation was about 8.4,and Km and Kcat were 1.24±016×10-5 mol/L and 1380±402 s-1 respectively.The Km of the large subunit was almost the same as that of ePA,but was about ten times smaller than that of the small subunit,which showed that the holoenzyme and the large subunit had stronger affinity for the substrate than the small subunit.The Kcat of the two subunits were close,1/6 and 1/3 of that of the holoenzyme respectively.Eight kinds of inhibitors were used to examine the mechanism.Pepstatin and E64　could　stimulate　the　degradation,while　TPCK,TLCK,PMSF,chymostatin and leupeptin could inhibit it.EDTA was non effective.The comparison between the degradation of BAEE and the fibrinolytic ativities was also made.更多还原