Abstract: Disclosed is an automatic computer-controlled bioreactor system for enzymatic synthesis of L-tryptophan which comprises a bioreactor linked to a computer equipped with an on-line indole assay device, in which the computer controls the feeding of indole, pyruvic acid and/or its salt and an ammonium salt into the bioreactor and feedback-controls the reaction in the bioreactor by indole concentration determined by the on-line indole assay device, wherein the feeding of indole and ammonium salt is controlled by a pre-defined profile that agrees with a tryptophanase activity profile and pyruvic acid and/or its salt is added at a predetermined time.

Abstract: Disclosed is a process for the preparation of N-benzyloxycarbonyl-.alpha.-L-aspartyl-L-phenylalanine methyl ester wherein a protease is used to catalyze the condensation reaction of N-benzyloxycarbonyl-L-aspartic acid with L-phenylalanine methyl ester in a system consisting of ethyl acetate, citrate buffer with the addition of glycerol as a dispersing agent.