嗜热链球菌双功能谷胱甘肽合成酶基因的克隆与表达

Cloning and Expression of Bifunctional Glutathione Synthetase from Streptococcus Thermophilus

谷胱甘肽作为体内主要的内源性抗氧化剂,在医药、食品、化妆品行业有重要的应用价值.以嗜热链球菌CICC20174为模板,扩增出双功能的γ-谷氨酰半胱氨酸合成酶/谷胱甘肽合成酶基因gsh F.插入表达载体p EASY-E1,转化大肠杆菌BL21(DE3),筛选出重组克隆.经过IPTG诱导,重组大肠杆菌菌体超声波破碎、镍柱亲和层析纯化后,SDS-PAGE显示一条85k Da的蛋白条带,与理论值相符.重组酶Gsh F可将谷氨酸、半胱氨酸、甘氨酸催化生成谷胱甘肽,重组大肠杆菌的胞内酶活为5.85U/L,比活力为0.083U/mg.

As a major endogenous antioxidant in vivo, glutathione（GSH） is widely used in pharmaceuticals, foods, and cosmetics. The gene gsh F encoding bifunctional γ-glutamylcysteine synthetase/glutathione synthetase was amplified from genomic DAN of Streptococcus thermophilus CICC 20174 and inserted into expression vector p EASY-E1. Transformed E. coli BL21（DE3） colonies were screened, and induced by IPTG for recombinant potein expression. After sonication and purification by Ni-chelating affinity chromatography, SDS-PAGE indicated a band of 85 k Da, consistent with theoretical value. Reconbinant Gsh F was used to catalyze glutathione formation. Its activity in E. coli culture was 5.85 U/L and the specific activity of purified enzyme reached 0.083 U/mg.