木聚糖酶融合基因的构建及其在大肠杆菌中的表达

以来源于Aspergillus usamii E001的高比活木聚糖酶XynⅡ为亲本,采用"中心模板法"将耐高温木聚糖酶TfxA的前31个氨基酸连接在XynⅡ的N端,构建出融合木聚糖酶TPL。将TPL在大肠杆菌BL21 (DE3)中进行表达,并对表达条件进行了优化,对表达产物的酶学性质进行了分析。结果表明,融合酶TPL最适pH为4.6,最适温度为45℃,和XynⅡ保持一致,但热稳定性有一定提高,在50℃处理10min,TPL和XynⅡ的残余酶活分别为15.72%和6.92%。

Construction of Hybrid Xylanase Gene and Its Expression in E.coli

The hybrid xylanase TPL was constructed by the ligation of the previous 31 amino acids of the N—terminus segment of Thermomonospora fusca xylanase TfxA to Aspergillus usarnii E001 xylanase Xy- nII.Core template method was deployed to get the hybrid gene txl.The hybrid gene txl,encoding the TPL, was correctly expressed in Escherichia coli BL21.The expression was also optimized under culture condi- tions.TPL was purified and its enzymatic properties were determined.The results revealed that the optimal temperature was 45℃and optimal pH was 4.6,which were not obviously improved compared with those of XynII.The thermostability of TPL was a little higher than XynII.The relative activity of TPL and XynII were 15.72% and 6.92% after incubating the properly diluted enzyme solutions at 50℃for 10 min.