Design of proteinase-cataiyzed synthesis of oligopeptides in an aqueous-organic biphasic system

Thermolysin-catalyzed condensation of N - (benzylxycarbyl) - glycyl - glycyl - L -phenylalanyl-L-leucine ethyl ester (Z-Gly-GlyPheLeuOEt), the precursor of the des-TyrMeucine enkephalin from N-(benzyl-oxycarbonyl)-glycyl-glycine (Z-GlyGly) and L-phenylalanyl-L-leucine ethyl ester (PheLeuOEt) was elucidated as a model reaction for the enzymatic synthesis of oligopeptides with many side reactions. In buffer solution, the yield of Z-GlyGly-PheLeuOEt was extremely low with considerable by-products. A large increase in both yield and purity became possible in the aqueous-organic biphasic system by the systematic selection of experimental conditions.