High isolated yields in thermolysin-catalysed synthesis of Z-l-aspartyl-l-phenylalanine methyl ester in toluene at controlled water activity

Z-l-Aspartyl-l-phenylalanine methyl and ethyl esters were synthesised enzymatically in toluene by means of the zinc protease thermolysin adsorbed onto Celite R-640®, which is a porous support able to control the hydration of the protein. The conversion of the two derivatised amino acids into the desired products was complete, leading to >90% isolated yields. Moreover, working with equimolar concentrations of the reactants no purification steps were required. Thermolysin adsorbed onto Celite R-640® is shown to be a practical tool to synthesise biologically active peptides in organic media.