ENZYMATIC-SYNTHESIS OF PEPTIDES USING N-P ROTECTED RACEMIC AMINO-ACIDS AS CARBOXYL COMPONENTS

Condensation of the N-Z- or N-Boc-protected DL-amino acids (or esters) with GlyNHNHPh in the presence of papain at pH=5.0(or 8.2) or alpha-c hymotrypsin at pH=10.0 formed the expected optically active protected oligopeptides. The reaction was carried out in an aqueous-organic mixe d solvent system and non-aqueous solvent system. These results indicat e that the amino acid ester as acyl donor was better than the correspo nding acid, The GlyNHNHPh as nucleophilic reagent was better than the corresponding ester, Both thermal and storage stabilities of alpha-chy motrypsin are greatly enhanced in nonaqueous solvents compared with wa ter system, The enzymatic peptide synthesis could also be carried out in dichloromethane with micro essential water (0.25%) and satisfactory results could be obtained.