绿色木霉β-葡萄糖苷酶的分离纯化及酶学性质

Separation,Purification and Enzymatic Properties of β-Glucosidase from Tridchoderma viride

针对绿色木霉AS3．3711产生的口．葡萄糖苷酶组分，先后运用包括乙酸铵沉淀、透析、SephadexG-150葡聚糖凝胶柱层析在内的一系列分离纯化技术对该纤维素酶进行纯化，得到β-葡萄糖苷酶纯化组分，并对该酶的酶学性质进行研究。纯化后酶液的蛋白质量浓度为8．12mg／mL、酶活力为4．08U／mL，纯化倍数达到18．48，十二烷基硫酸钠．聚丙烯酰胺凝胶电泳（sodiumdodecylsulfatepolyacrylamidegelelectrophoresis，SDS．PAGE）测定分子质量为66．0kD。绿色木霉卢一葡萄糖苷酶在酸性条件下稳定性良好，最适pH值为5．0；在温度60-70℃能长时间保持较高酶活力，最适反应温度为60℃。金属离子中，Ca2＋、Mg2＋、K＋对绿色木霉AS3．3711伊葡萄糖苷酶活力起到促进作用，Ca2＋促进作用最强；而Zn2＋、Fe3＋对该酶有抑制作用，Ar、Cu2＋、Hg2＋重金属离子使肛葡萄糖苷酶几乎丧失了全部活性。

An extracellular β-glucosidase produced by Trichoderma viride AS3.3711 was separated and purified by ammonium acetate precipitation, dialysis and Sephadex G-150 column chromatography. The results of enzyme characterization showed that the protein concentration of the purified enzyme solution was 8.12 mg/mL, and the β-glucosidase activity was 4.08 U/mL, with a purification factor of 18.48. Its molecular weight was 66.0 kD. The β-glucosidase from Trichoderma viride displayed a strong stability under acidic conditions and its optimum pH value was 5.0. In the range of 60-70 ℃, it could still maintain a high enzyme activity for a long time with an optimum reaction temperature of 60 ℃. Some metal ions including Ca2＋, Mg2＋ and K＋ improved its activity with Ca2＋ having the strongest effect. However, Zn2＋ and Fe3＋ inhibited the enzyme. Heavy metal ions such as Ag＋, Cu2＋ and Hg2＋ almost totally inactivated its activity.