Abstract: Objective: L-Tryptophan was enzymatically synthesized by tryptophanase in genetic engineering strain WW-11 from L-cysteine and indole. Methods:Tryptophanase in engineeringstrain was expressed by IPTG induction. The engineering strain free cells with the highest enzymeactivity were used as enzyme source in the reaction mixture. L-Tryptophan accumulated in the reaction mixture was analysed and determined by paper chromatography and amino acid analyzer Results:An yield of 1.18g of L-tryptophan was obtained from 0.75 g of L-cysteine and 0.75g of indolein 80 mL reaction mixture shaking for 48 h at 37 ℃. The conversion rate was 93.2% for L-cysteineand 90.1% for indole. After isolation and purification, the crystals were identical with authentic Ltryptophan, in respects of melting point, optical activity and IR-spectrum. Conclusion:Tryptophanase in genetic engineering strain could effectively catalyze L-cysteine and indole tosynthesize L-tryptophan. This enzymatic synthesis method is one of the more effective methods forthe industrial production of L-tryptophan.

Key words: L-Cysteine, L-Tryptophan, Tryptophanase genetic engineering strain, Synthesis