小鼠重组釉蛋白32000多肽的原核表达和纯化

摘要

目的 在大肠杆菌中表达小鼠重组釉蛋白32 000多肽,为进一步制备抗鼠釉蛋白抗体和釉蛋白功能研究奠定基础.方法 利用聚合酶链反应(PCR)法扩增出编码小鼠釉蛋白32 000多肽的cDNA序列,将所得基因片段插入pGEM-T Easy质粒载体,转化大肠杆菌JM109后挑取阳性克隆,提取重组质粒DNA,并经酶切鉴定后将所克隆的序列312 bp片段连入原核表达载体pGEX-4T1,并于大肠杆菌BL21中诱导表达,行SDS聚丙烯酰胺凝胶电泳分析.结果 成功构建了重组表达载体pGEX-4T1-EN312,并经异丙基硫代半乳糖苷诱导后,可见相对分子质量(Mr)为47×103的融合蛋白.结论 利用pGEX-4T1-EN312-BL21体系成功获得了小鼠重组釉蛋白32 000多肽在大肠杆菌中的原核表达和初步纯化.%Objective To examine the expression of the recombinant mouse 32 000 enamelin in Escherichia coli(Ec).Methods The desired 32 000 enamelin cDNA fragment was obtained by polymerase chain reaction (PCR).The segment was inserted into pGEM-T Easy vector and transformened into Ec JM109.The positive clone was analyzed by restriction endonuclease mapping and DNA sequencing.The 312 bp aimed fragment was inserted into pGEX-4T1 vector and the recombinant protein was induced by isopropyl thiogalactoside in Ec BL-21.Results The recombinant expressive plasmid pGEX-4T1-EN312 was successfully constructed.After induced with isopropythio-galactoside,a new fusion protein band near Mr 47 ×103 appeared on SDS polyacrylamide gel electrophoresis.Conclusions pGEX-4T1-EN312-BL21 system is used successfully to express and purify recombinant mouse 32 000 enamelin polypeptide.