N-乙酰-D-葡萄糖胺-2-差向异构酶基因的克隆、表达及产物纯化

目的：从猪肾中提取RNA,从中克隆出N-乙酰-D-葡萄糖胺-2-差向异构酶（GNE）基因,并在大肠杆菌E.coli BL21（DE3）中表达。方法：从猪肾中提取总RNA,通过RT-PCR克隆出GNE基因,经测序,感受态大肠杆菌E.coli DH5a转化,质粒抽提,鉴定以及大肠杆菌BL21（DE3）转化表达,通过His-tag亲和纯化（Ni Sepharose 6 Fast Flow）,G-25柱脱盐,SDS-PAGE电泳检测。结果：RNA提取物经紫外分光光度计检测OD260/OD280=1.77,说明无明显的蛋白质和酚污染。RT-PCR扩增目的片段,测序证明该基因的ORF为1 206 bp,编码402个氨基酸组成的酶蛋白（GNE）。SDS-PAGE显示,纯化蛋白为45 kD的单一条带,与基因序列推测值一致。结论：GNE基因已被成功地克隆和表达。

Cloning,expression and purification of N-acetyl-D-glucosamine-2-epimerase

Objective：To clone the gene of N-acetyl-D-glucosamine-2-epimerase according to RNA extracted from pig kidney and express it in E.coli BL21（DE3） and then purify the product.Methods：RNA was extracted from porcine kidney to clone the gene of N-acetyl-D-glucosamine-2-epimerase with RT-PCR followed by sequencing.Recombinant plasmid was converted into E.coli DH5a and to identify it followed by the conversion of the recombinant plasmid in E.coli BL21（DE3） and expression.The protein was purified by His-tag（Ni Sepharose 6 Fast Flow）,desalted by G-25 column and identified by SDS-PAGE.Result：RNA was extracted from porcine kidney and identified with ultraviolet spectrophotometer：OD260=0.0346,OD280=0.0195,OD260/OD280=1.77（between1.7 and 2.2）,it showed that there was no protein and phenol contamination.Amplification of GNE with RT-PCR,the sequence length of GNE was 1 206 bp encode for 402 amino acids.The molecular weight of purified protein was 45 kD revealed by SDS-PAGE,which was consistent to the analysis based on gene sequence.Conclusion：N-acetyl-D-glucosamine-2-epimerase gene is successfully cloned and expressed in E.coli BL21（DE3）.