Methanolysis of the pyrrolidone ring of amino-terminal pyroglutamic acid in model peptides

Abstract

Treatment with HCl MeOH opened the pyrrolidone ring of the amino-terminal pyroglutamyl residue in several small peptides. Among the peptides tested, only Pyr-Gly and Pyr-Gly-Gly gave evidence of partial cleavage of peptide bonds. Several pyroglutamyl peptides, including new compounds Pyr-Lys, and Pyr-Asp-Ile-Gln-Leu, and some blocked derivatives of these peptides were synthesized. The chromatographic and staining properties of pyroglutamyl dipeptides and of the products of these peptides after HCl MeOH treatment were determined.