木聚糖酶Xyn43A基因在大肠杆菌及毕赤酵母中的表达比较

Expression of xylanase Xyn43A gene in Escherichia coli and Pichia pastoris

根据木聚糖酶Xyn43A基因序列,设计特异性引物,以p MD18-T-Xyn43A重组质粒为模板克隆Xyn43A成熟肽基因,将该基因分别克隆到大肠杆菌表达载体p ET-28a和毕赤酵母表达载体p PIC9K中,分别在大肠杆菌BL21及毕赤酵母GS115中表达。重组酶在大肠杆菌中胞内表达,比酶活力可达61.43 U/mg。重组酶在毕赤酵母中分泌表达,比酶活力可达145.24 U/mg。酶学性质显示,BL21-Xyn43A、GS115-Xyn43A重组酶最适温度、p H相同均为45℃、p H 5.0。GS115-Xyn43A温度稳定性、p H稳定性均优于BL21-Xyn43A。

The gene of Xyn43 A mature peptide was amplified with a template of the recombinant plasmid p MD18-T-xyn43 A and specific primers designed according to the c DNA sequence of Xyn43 A from Aspergillus niger XZ-3S. It was respectively inserted into vectors of p ET-28 a and p PIC9 K and then transformed to Escherichia coli BL21（ DE3）and Pichia pastoris GS115,respectively. The recombinant xylanase was expressed in the cytoplasm of E. coli,and the specific activity of the recombinant enzyme was 61. 43 U / mg. The enzyme was extracellular secretion in P. pastoris,and its specific activity was 145. 24 U / mg. The optimum temperatures and p H values of BL21-Xyn43 A and GS115-Xyn43 A were both 45 ℃ and p H 5. 0. The temperature stability and p H stability of GS115-Xyn43 A were better than those of BL21-Xyn43 A.