鸭血清胆碱酯酶的纯化及性质研究

首次采用新技术双水相萃取方法作为鸭血清胆碱酯酶(EC.3.1.1.8 CHE) 纯化的第一步,后经 DEAE-Sephadex A50,sephadex G200 柱层析,获得电泳纯鸭血清胆碱酯酶,提纯倍数1018倍,酶活力回收43.4%,比活274.9U/mg。鸭血清胆碱酯酶性质研究表明:此酶是糖蛋白和酸性蛋白水解酶,等电点 4.2 左右,最适 pH7.5 左右;对底物碘化硫代丁酰胆碱的 K_m=9.8×10^-5mol/L;SDS-PAGE 电泳和聚丙烯酰胺梯度电泳表明,鸭血清胆碱酯酶以相同亚基组成的不同聚合体形式存在,亚基分子量 78000,具有完整的酶活性.不同聚合体带电状态相同.

Studies on the Purification and Properties of Duck Serum Choline Esterase

The method of PEG/phosphate salt two phase extraction as the first step of purification to prepare duck serum choline esterase was first used in this paper.The procedure was not only simple,rapid but also high in the activity recovery of the choline esterase.The purified choline esterase with specific activity 279.9 U/mg was followed by DEAE-sephadex A50 and sephadex G200 chromatography.The choline esterase was purified 1018-fold and the activity recovery of 43.4 per cent was obtained.Studies on the properties of the choline esterase showed that it was a kind of glycoproteins and acid hydrolases. The isoelectric point of 4.2 and the optimum pH of 7.5 were obtained. The K_m of 9.8×10^-5mol/L with butyryl-thiocholine iodide was determined. SDS and polyacrylamide gel electrophoresis showed that the choline esterase existed in the different polymers composed of the same subunit. The molecular weight of subunit was 78000, and the subunit had the activity of the whole choline esterase.