摘要
从pSom5中提纯生长抑制激素基因片段,在体外与大肠杆菌pBD_2质粒DNA重组连接,转化受体细胞D_2A_1,获得7株工程菌,在IPTG诱导下进行表达。采用β-半乳糖苷酶底物亲和层析法纯化,得到一纯净的分子量为50000道尔顿左右的蛋白质。对此蛋白质及其经CNBr化学裂解的产物进行放射免疫分析,证实化学合成的生长抑制激素基因已在大肠杆菌D_2,A_1中成功地表达,每升培养基中获得生长抑制激素41.69mg,占菌体总蛋白质的0.71%。
Somatostatin gene fragment extracted and purified from plasmid pSom5 bacterium was ligated with the plasmid pBD2 DNA- Transformation of E. coli D29A1 with the chimeric plasmid DNA led to the synthesis of a polypeptide including the sequence of amino acids corresponding to somatostatin. The chimeric protein (50000 dalton) was purified and characterized by the β-galactosidase affinity chromatography and the expression of the somatostatin gene in E. coli D29A1 is certain after the radioimmunoassay of the chimeric protein and its mixture by treatment with cyanogen bromide.
