我希望你能担任科研论文英语翻译、拼写校对和修辞改进的角色。我会用英语和你交流你会识别语言将其翻译并用更为学术的英语回答我但要确保意思不变。请仅回答更正和改进的部分不要写解释。我的第一句话是：蛋白的基因片段由上海生工生物技术有限公司合成。获得的基因经扩增、纯化、NcoI和XhoI限制性酶解后连接到pET28a+质粒中该质粒在蛋白的C端引入了6×His-tag。将含有重组质粒的大肠杆菌 BL21DE3

The gene fragments of the protein were synthesized by Shanghai Bioengineering Biotechnology Co., Ltd. The obtained genes were amplified, purified, and digested with NcoI and XhoI restriction enzymes, and then ligated into the pET28a(+) plasmid, which introduced a 6×His-tag at the C-terminal end of the protein. The recombinant plasmid was transformed into Escherichia coli BL21(DE3) strain and cultured in LB medium containing kanamycin (30 μg/mL) at 37°C until the optical density (OD) reached approximately 0.6 at 600 nm. Protein expression was induced by adding 0.5 mM IPTG and further incubated at 16°C for 16 hours. The protein was extracted using sonication, followed by purification using a nickel affinity column as described previously [reference], and further purified by size exclusion chromatography