SDS-subtilisin catalyzed synthesis of tetra-peptides containing multifunctional amino acid residues in ethanol

The role of acyl donor structure on the course of peptide bond formation catalyzed by SDS-subtilisin in ethanol was investigated. In the reaction ZAlaAlaLeuOR+HPhepNA→ZAlaAlaLeuPhepNA, nearly quantitative product yields were observed after 2 h, regardless of whether an activated (R=CH3, p-C6H5Cl) or non-activated (R=H) acyl donor was used. It was found that the enzyme can accept as acyl donors N-protected tri-peptides containing basic or acidic amino acid residues in the P1-position. Tetra-peptides of general formula ZAlaAlaP1P1′pNA, where P1=Glu, Asp, Lys, Arg or His and P1′=Phe, Arg or Glu have been obtained in good yield.