Expression of γ-Glutamyl Transpeptidase(γ-ggt)from pET Plasmid Using Lactose as Inducer

The optimization of expression of the cloned γ-glutamyl transpeptidase(γ-ggt)gene in Escherichia coli strain BL21(DE3) by using lactose as the inducer was reported in this paper.It was found that expression level of γ-ggt achieved the highest after the BL21(DE3) was induced for 4 h with lactose 1 g/L begining from strain density of OD600=0.9.The expression level of γ-ggt protein was about 15.2% of the total cellular proteins.The inducing efficiency of lactose was lower than that as IPTG(isopropyl-β-D-thiogalactopyranoside),but because of the toxicity and the high cost of the latter,lactose is a promising inducer in the lac-promotor based expression system.