龋病替代疗法中乙醇脱氢酶基因在大肠杆菌中的表达

目的 在成功构建运动发酵单胞菌乙醇脱氢酶基因（adhB）置换变链乳酸脱氢酶基因（1dh）重组质粒pMDLA的基础上，构建表达栽体pET-28a-adhB，在大肠杆菌中进行目的基因的诱导表达。方法 应用DNA重组技术构建表达栽体，通过SDS-SAGE和乙醛指示平扳鉴定目的基因的表达效率。结果 成功构建了表达栽体pET-28a-adhB，通过SDS-PAGE检测可见特异性蛋白表达条带，在乙醛指示平扳上可见阳性菌落。结论 根据测序及大肠杆菌表达结果，可确定该重组质粒中adhB已完全替换ldh，为下一步构建乳酸脱氢酶活性缺陷的变链突变株奠定基础。

Expression of alcohol dehydrogenase gene in Escherichia coli for replacement therapy of dental caries

Objective To express the gene of alcohol dehydrogenase in E. coll. , which was obtained from the recombinant vector of pMDLA for the replacement therapy of dental caries. Methods adhB gene was digested by restriction enzymes from the recombinant vector and inserted into the expression vector pET - 28a and then expressed in E. coli BL21. Results Expression vector of pET - 28a - adhB was successfully constructed. A specific 40,000 - protein band could be seen on the SDS - PAGE gel induced by IPTG and positive clones were observed on aldehyde indicator plates. Conclusion It is comfirmed that the ldh gene was replaced perfectly by adhB gene,which is a start for the further study of the constuction of LDH - deficient mutant of S. mutans.