Abstract: Condensation of the N-Z-or N-Boc-protected DL-amino acids(or esters)withGlyNHNHPh in the presence of papain at pH=5.0(or 8.2)or α-chymotrypsin at pH=10.0formed the expected optically active protected oligopeptides. The reaction was carried out inan aqueous-organic mixed solvent system and non-aqueous solvent system.These results indicate that the amino acid ester as acyl donor was better than the corresponding acid.The GlyNHNHPh as nucleophilic reagent was better than the correspondingester. Both thermal and storage stabilities of α- chymotrypsin are greatly enhanced in nonaqueous solvents compared with water system.The enzymatic peptide synthesis could alsobe carried out in dichloromethane with micro essential water(0.25%)and satisfactory results could be obtained.

Key words: Enzymatic peptide synthesis, Recemic amino acids, α-Chymotrypsin, Papain, DEPBT