Enzymatic syntheses of N-protected Leu-enkephalin and some oligopeptides in organic solvents

Article abstract of DOI:10.1016/S0040-4020(98)00737-6

Enzymatic syntheses of bioacitive pentapeptide, N-protected Leu- enkephalin and some other oligopeptides in organic solvents were studied. The stereoselectivity of the enzymatic reaction was examined by using racemic substrates. Different enzymes, solvent systems and protecting groups were compared. The importance of the essential water was addressed. The side chain of tyrosine was not protected during all the enzymatic reactions, P-DL-AlaOY (P=Z or Boc, Y=H or Me) and P-DL-TyrOEt were coupled with GlyNHNHPh by papain and α-chymotrypsin in mixed solvent or organic solvent to obtain the expected optically pure products P-L-AlaGlyNHNHPh and P-L-TyrGlyNHNHPh respectively in good yield. Two sweetener precursors, ZAspXaaOR (XaaOR=PheOMe or AlaOcHex) were synthesized by thermolysin in tert-amyl alcohol and some reaction conditions were optimized to get the best yield. Full enzymatic synthesis of N-protected Leu-enkephalin ZTyrGlyGlyPheLeuOH was investigated using α-chymotrypsin and thermolysin as catalysts in dichloromethane and tert-amyl alcohol.