中文摘要：

目的：研究一组新型蚯蚓脱氧核糖核酸酶（earthworm desoxyribonucleases，EWDs）的主要生化性质。方法：采用SDS—PAGE、MALDI—TOF、紫外分光光度方法。结果：确定了EWD1，EWD2、EWD3（总称为：EWDs）的分子量分别为157．2kDa，69．1kDa和63．5kDa。37℃，pH4．6以小牛胸腺DNA为底物时，EWDs的Km值分别为1．58mg／ml，3．95mg／ml，1．52mg／ml；Vmax分别为5．36mg／（ml·min），2．87mg／（ml·min），4．89mg／（ml·min）。EWDs在55℃保温10min，酶活性完全丧失，在40℃以下酶活性都比较稳定。这3种脱氧核糖核酸酶最适pH值分别是5．2，4．4，4．8，酸性条件下较稳定。Mn^2＋，Ca^2＋是蚯蚓组织脱氧核糖核酸酶EWD1，EWD2，EWD3的抑制剂，Mg^2＋对EWD3有较明显的抑制作用。结论：蚯蚓组织中发现的脱氧核糖核酸酶EWDs具有独特的酶学特征，不同于已经发现的DNaseⅠ和DNaseⅡ，是种新型的脱氧核糖核酸酶，但其作用机理和分类有待于进一步的研究和归类。

英文摘要：

Objective：To study the main characteristics of earthworm deoxyribonucleases（EWDs）. Methods： SDS-PAGE and MADLT-TOF were used to the study. Results ： The molecular weights of EWDs （ EWD1 , EWD2 and EWD3 ） were 157.2kDa,69. lkDa and 63.5kDa respectively. Under the condition of 37℃ ,pH4.6 and take calf thymus DNA as substrate ,the Km values of EWDs were 1.58mg/ml, 3.95mg/ml, 1.52mg/ml and the Vmax were 5. 36mg/（ ml ·min）, 2. 87mg/（ ml · min） and 4. 89mg/（ ml·min）, respectively. The EWDs were sensitive to temperature, which didn＇t show any activity when the temperature rises to 55℃ for 10 min and showed stability below 40℃. The optimum pH were 5.2,4.4,4.8 ,respectively. Mn^2＋ , Ca^2＋ were inhibitors of EWDs, and Mg^2＋ had negative effect on EWD3 enzyme activity. Conclusion： EWDs has unique characteristics which are different from DNases known before.