家蚕丝素结晶区高度重复多肽[GAGAGA]_(16)和[GAGAGS]_(16)的融合蛋白优化表达

Optimization of Expression of Highly Repetitive Polypeptides [GAGAGA]_(16) and [GAGAGS]_(16) From Bombyx mori Silk Fibroin Crystalline Domain

为了给深入研究家蚕丝素结晶区的典型肽段结构提供素材,对设计的GST-tag家蚕丝素结晶区典型多肽[GAGAGA]16和[GAGAGS]16的融合蛋白KGA、KGS进行了表达条件优化试验。结果表明,pGEX-KGA和pGEX-KGS表达载体能够有效表达家蚕丝素结晶区的2种典型多肽,KGA和KGS的最佳表达诱导剂IPTG的浓度分别为1.4mmol/L、1.0 mmol/L,诱导时间为5 h。在此优化条件下,KGA和KGS在大肠杆菌（E.coli）中的表达量分别达75 mg/L、110 mg/L。诱导起始时大肠杆菌的菌密度（OD600为0.4-3.0）对2种融合蛋白的表达效率没有显著影响。

In order to study structures of the typical peptides from silk fibroin crystalline domain by gene engineering,the expression conditions were optimized for expressing designed GST-tagged crystalline peptides[GAGAGA]16 and[GAGAGS] 16 fusion proteins（KGA and KGS）.The results showed that：fusion proteins KGA and KGS could be expressed efficiently using the expression vectors pGEX-KGA and pGEX-KGS.The best IPTG concentrations for KGA and KGS were 1.4 mmol/L and 1.0 mmol/L respectively,and the best induction time was 5 h.Under these optimum conditions,yields for KGA and KGS reached 75 mg/L and 110 mg /L of culture,respectively.When OD600 of the E.coli culture ranged from 0.4 to 3.0 before induction,no obvious influence on the expression of these two fusion proteins was observed