Abstract:

By using the previously-established model of quantitative structure-activity relationships （QSAR） for melittin, six genes of melittin analogues were predicted and designed. Then, by adopting the Pichia pastoris expression system, the recombinant plasmid of pPICZα-A-Mel was constructed and transformed into yeast by electric shock for the secretory expression in Pichia pastoris GS115, with α-factor as the secretory signal. The expression products were purified via 6 × His affinity chromatography after screening and inducing, and were then confirmed by Tricine-SDS-PAGE. The results show that （ 1 ） four of the expression products of the six newly-designed genes reveal stronger antibacterial activity than the recombinant natural melittin, while two of them are of weaker activity; （2） the inhibition titer of Analogue [ C ] with the strongest antibacterial activity is i. 62 times that of the recombinant natural melittin ; （3） the inhibitory activity of Analogue [ B ] with the highest expression level is next to that of [ C] ; and （4） the hemolytic activities of the six analogues are all less than 1/15 as compared with that of the recombinant natural melittin. It is thus concluded that the optimized design of melittin molecular is reasonable and feasible in maintaining or improving the antibacterial activity and in reducing the hemolytic activity.

Key words: melittin analogue, molecular design, gene expression, biological activity, structure-activity relationship