Thermolysin-Catalyzed Synthesis of Peptide Amides

Enzymatic condensation by thermolysin between various amino acid amides and Naprotected or unprotected peptides was examined.As models, three protected tetrapeptide amides, Boc-Trp-Met-Asp-X, Boc-Ser-Glu-Ala-X and Boc-Ser-Lys-Ala-X, and two unprotected tetrapeptide amides, H-Trp-Met-Asp-X and H-Phe-Met-Arg-X, were prepared [X=Phe-NH2, Leu-NH2, Phe-NHEt, Val-NH2, Ala-NH2, (p-fluoro) Phe-NH2], and the effects of various experimental conditions (pH, solvent and time) were examined.In addition, the C-terminal of oxidized insulin B-chain was elongated to an amide by addition of various amides mentioned above with the aid of thermolysin.