Protease-catalyzed synthesis of a precursor dipeptide, Z-Asp-Val-NH2 of thymopentin, in organic solvents.

The protease-catalyzed, kinetically controlled synthesis of a precursor dipeptide, Z-Asp-Val-NH(2) of thymopentin (TP-5), in organic solvents was studied. Z-Asp-OMe and Val-NH(2) were used as the acyl donor and the nucleophile, respectively. An industrial alkaline protease alcalase was used to catalyze the synthesis of the target dipeptide in water-organic cosolvent systems. The conditions of the synthesis reaction were optimized by examining the effects of several factors, including organic solvents, water content, temperature, pH, and reaction time on the yield of Z-Asp-Val-NH(2). The optimum conditions using alcalase as the catalyst are pH 10.0, 35 degrees C, in acetonitrile/Na(2)CO(3)-NaHCO(3) buffer system (9:1, V/V), reaction time 5 h, with a yield of 63%. The dipeptide product was confirmed by LC- MS.