对硫磷真菌降解酶的分离纯化和性质

黑曲霉AspergillusnigerY－8在液体培养基中30℃培养5d，其菌体用超声波破碎后，经硫酸铵沉淀、DEAE-纤维素层析、Sephadex－100凝胶过滤，得到凝胶电泳均一的对硫磷降解酶，其比活为6.94，提纯倍数为13.6倍，收率为17．4％。酶作用的最适温度是50℃，最适pH为7.5，在40℃以下和pH6.0～9.0之间稳定，此酶为单亚基蛋白，凝胶过滤法测得分子量为42000，含糖14.6％，SDS、Hg2+、Ag+、Fe3+对酶有强烈的抑制作用，金属螫合剂EDTA对酶活无影响。此酶对甲基对硫磷、敌敌畏、亚胺硫磷也有较好的降解作用，当以对硫磷为底物时，Km为0.43mmol／L，Vmax为1.24μmol·mg-1·min-1。

PURIFICATION AND PROPERTIES OF PARATHION-DEGRADING ENZYME FROM ASPERGILLUS NIGER Y-8

Parathion-degrading enzyme from Aspergillus niger Y-8 cell of culture at 30℃, 5d was purified to SDS-PAGE homogenous by (NH4)2 SO4 precipitation, DEAE-cellulose chromatography, Sephadex G-100 gel filtration with 13.6-fold purification,17.4% recovery and 6.94u / mg specific activity. The enzyme, containing 14.6% of carbohydrate, was a monomer protein with molecular weight of 42000 Dalton. The optimal conditions for activity were pH7.5, temperature 50℃ respectively. The enzyme was stable over the range of pH6~9 and below 40℃, the activity was inhabited by SDS、 Hg2+、 Ag+, Fe3+, the enzyme can degrade others organophosophorus pesticides such as methylparathion, dichiovos and so on. The Km and Vmax of the enzyme was 0.43mmol / L and 1 .24μmol / L. mg - 1.min - 1, respectively.