Chemo-enzymatic synthesis of tripeptide RGD diamide in organic solvents

The tripeptide BzArgGlyAsp(NH2)2 was synthesized by a combination of chemical and enzymatic methods in this study. First of all, GlyAsp(NH2)2 was synthesized by a novel chemical method in three steps including chloroacetylation of l-aspartic acid, esterification of chloroacetyl l-aspartic acid and ammonolysis of chloroacetyl l-aspartic acid diethyl ester. Secondly, kinetically controlled synthesis of BzArgGlyAsp(NH2)2 catalyzed by trypsin in organic solvent was conducted. The optimum conditions are pH 8.0, 30 °C in ethanol/Tris-HCl buffer system (85:15, v/v) for 80 min in the maximum yield of 74.4%.