Peptide synthesis catalyzed by subtilisin-72 in organic solvents

The solubility, stability, and activity of native subtilisin 72 and of its complex with SDS were comparatively studied in a number of polar organic so lvents. Subtilisin was found to catalyze peptide bond formation when suspen ded in acetonitrile or solubilized as a complex with SDS in ethanol and iso propanol. Tripeptide Z-Ala-Ala-Leu-pNA, tetrapeptides A-Ala-Ala-P-1-P'(1)-B , where A = Z or Abz; P-1 = Leu, Phe, Met, Trp, Ile, Tyr, Phe(NO2), or Glu( OMe), P'(1) = Leu, Phe, Glu, Ala, Ile, Val, or Arg; B = NH2, pNA, or 2-(2,4 -dinitrophenyl)aminoethylamine residue (Ded); pentapeptides Z-Ala-Ala-Leu-A la-Ala-pNA and Z-Ala-Ala-Leu-Ala-Phe-pNA; and hexapeptide Abz-Val-Ala-Phe-P he-Ala-Ala-Ded were synthesized using the SDS-subtilisin complex. The compl ex also efficiently catalyzed the oligomerization of tripeptide H-Phe-Ala-L eu-OCH3 in ethanol, which resulted in a 63 : 37 mixture of trioligomer and tetraoligomer. It was demonstrated that SDS-subtilisin is a much more effic ient catalyst than the suspension of native enzyme.