星天牛幼虫肠道木聚糖酶的纯化和性质

星天牛Anoplophora chinensis (Frster)幼虫肠道匀浆液经80%丙酮沉淀、Q-Sepharose阴离子交换柱层析、PAGE制备电泳等方法纯化后，获得在SDS-PAGE上呈现单一区带的木聚糖酶。该酶的分子量约25 kD，等电点约4.0，最适温度50℃，最适pH 5.4，pH 3.0～7.8对酶活性的恢复无大的影响， 50℃保温2 h仍有60%酶活性。Hg²⁺、M_nO^-4、变性剂SDS完全抑制该酶活性， Cu²⁺、Mn²⁺、Ag⁺、Zn²⁺、Pb⁺、脲对酶活性有强烈的抑制作用。该酶具有水解纤维素的交叉活性，其K_m值为2.47 mg/mL，V_max为0.6 IU/mL。

Purification and properties of xylanase from Anoplophora chinensis (Forster)

A xylanase was purified from the homogenate of alimentary canal of Anoplophora chinensis (Froster) by acetone precipitation, Q-Sepharose ion-exchange chromatography and preparative PAGE. The xylanase had a molecular mass approximate 25 kD and pI 4.0. For the action of the enzyme isolated, the most optimal temperature and pH were 50℃ and 5.4 respectively. About 60% of the enzyme activity remained after incubating it at 50℃ for 2 hours. The enzyme could be inhabited by Hg²⁺,MnO^-4,SDS, Cu²⁺, Mn²⁺, Ag⁺, Zn²⁺, Pb⁺ and Urea. It could hydrolyse carboxymethylcellulose (CMC). The enzyme had a K_m of 2.47 mg/mL and a V_max of 0.6 IU/mL for birchwood xylan at 50℃ and pH 4.4