Expression of recombinant human extracellular TRAIL fragment in Escherichia coli using lactose as inducer

The optimal conditions for the expression of recombinant human extracellular TRAIL fragment in Escherichia coli strain BL21(DE3) by using lactose as the inducer were studied.The highest expression level of hTRAIL was found after the BL21(DE3) had been induced for 7h with 0.5g·L-1 lactose beginning from strain density of OD600 0.8.The expression level of hTRAIL protein was about 45.0% of the total bacterial proteins.After protein purification,the purity of hTRAIL was higher than 93% and it could induce apoptosis of HeLa cells.The induction efficiency of lactose is better than that of IPTG,which proved that lactose could be a promising inducer in the future experiments.