Optimization of Recombinant Human α Calcitonin Gene-related Peptide Expression in E.coli

In order to improve the expression level of human α calcitonin gene-related peptide (hαCGRP), the growth conditions of the engineering strain, that confirmed by transforming the recombinant plasmid pET-hαCGRP which constructed by our team into the host E.coli BL21trxB(DE3)pLysS were studied,which remarkably influenced the final yield of protein expression. With the aid of SDS-PAGE and YLN2000 gel image analysis, it was found that the best expressed condition was that the induction was started as OD_(600) reached 0.6～0.8 by adding IPTG to a final concentration of 0.75 mmol/L and then continued incubation 4 hours at 37 ℃ (180±5 r/min) in the LB medium containing 50 mg/L ampicillin with shaking flasks. The maximum yield of fusion protein was about70%～80% of the total mass of bacterial proteins. Furthermore the soluble form of the target protein makes convenience for next purification work.