Improvement of Cecropin AD and Buforin Ⅱ Expression Vector and Optimization for Fusion Protein Expression Conditions

Effects of expression strains, plasmid stability and inducing conditions were studied on improving the expression efficiency of Cecropin AD and Buforin Ⅱ fusion protein in recombinant Escherichia coli.According to the result of SDS-PAGE, E.coli BER2566was accepted as expression strain.Plasmid pET (K) -Trx-CAD-Buforin Ⅱ with kanamycin resistant gene was constructed to improve the plasmid stability and protein expression.Inducing conditions including IPTG concentration, induction time and inducing time length were optimized.With the optimal conditions, the highest expression level of fusion protein was obtained in recombinant E.coli at the level of OD600 0.8and final IPTG concentration of 0.8mmol·L-1 for 5hinducing, which was more than 50%of the total protein in E.coli.