灰绿曲霉β-葡萄糖苷酶的分离及特性

Purification and Properties of β-glucosidase from Aspergillus glaucus EU7-22

目的：利用灰绿曲霉EU7-22发酵产纤维素酶,从中分离到β-葡萄糖苷酶,分析其理化特性,确定其最佳活性条件。方法：灰绿曲霉EU7-22发酵液离心后,上清液经硫酸铵沉淀、Phenyl 6 Fast Flow（highsub）疏水层析和Sephacryl S-200凝胶层析,获得纯化的β-葡萄糖苷酶。结果：纯酶的比活性为5.1 IU/mg,得率为13.89%。SDS-PAGE凝胶电泳分析表明该酶是单亚基蛋白,其分子量为56.2 kDa。在pH4.0~6.0范围内,β-葡萄糖苷酶具有较高的稳定性,该酶的最适酶促反应pH为5.0。当β-葡萄糖苷酶在温度低于60℃的缓冲液中温育1 h后,酶活损失不大,表现了较好的稳定性;当该酶在温度高于60℃的缓冲液中温育1 h后,酶活迅速丧失。β-葡萄糖苷酶在70℃时具有最大催化活性。结论：灰绿曲霉EU7-22发酵产生的β-葡萄糖苷酶具有较高活性,具有分子量较小、最佳催化温度较高的特点。

Objective：β-glucosidase produced by Aspergillus glaucus EU7-22 was purified and characterized.Method：The β-glucosidase of Aspergillus glaucus EU722 was purified from ferment supernatant liquid by three steps of purification,ammonium sulfate precipitation（80%,W/V）,Phenyl 6 Fast Flow（high sub） column chromatography and Sephacryl S-200 column chromatography,with a specific activity of 5.1 IU/mg and a yield of 13.89%.Result：The purified β-glucosidase was determined as a monomeric protein with a molecular weight of 56.2 kDa.The enzyme exhibited high stability when it was kept in the buffer at pH 4.0～6.0 and at the temperature below 60℃.β-glucosidase exhibited its optimal activity at 70℃.Conclusion： β-glucosidase produced by Aspergillus glaucus EU7-22 with small molecular showed high activity under the optimal conditions.