Abstract: Betaine-homocysteine methyl transferase (BHMT), which is a methyl-metabolizing enzyme , can catalyze methyl of betaine shifting to homocysteine, forming methionine. In this study, pET30a-SsBHMT was expressed in Escherichia coli. The strains, IPTG concentrations and induction time were optimized. The results showed that the expressed protein mainly existed in the form of inclusion bodies. After optimization, the target protein expression levels were increased both in supernatant and precipitate, but mainly in the form of inclusion bodies. In the strain of ER2566, the expression level of recombinant protein was high when induced for 10 h by 0.4 mmol/L of IPTG at 37℃. The results laid a foundation for further studies on the protein purification and antibodies preparation.

Key words: prokaryotic expression, BHMT gene, condition optimization

摘要： 甜菜碱高半胱氨酸甲基转移酶（BHMT）是一种甲基代谢酶，催化甜菜碱转甲基到高半胱氨酸生成甲硫氨酸。对含有pET30a-SsBHMT重组质粒的菌株进行诱导表达分析，通过对菌株、IPTG诱导浓度、时间等诱导表达条件进行优化，结果表明：该目的蛋白主要以包涵体的形式出现；经过条件优化，目的蛋白表达量在上清和沉淀中均有所增加，但仍主要以包涵体的形式存在；大肠杆菌菌株ER2566为适合目的蛋白表达的菌株;在37℃，IPTG浓度为0.4 mmol/L，诱导时间为10 h的条件下，目的蛋白表达量最多。研究结果为进一步蛋白纯化与抗体制备奠定了基础。

关键词: 原核表达, BHMT基因, 条件优化