Sequence dependence in the formation of pyroglutamyl peptides in solid phase peptide synthesis

Abstract
A study was conducted to determine the effect of amino acid sequence on the rate of formation of pyroglutamate (pyrrolidone carboxylate) residues from amino‐terminal glutaminyl residues in peptides. The extent of cyclization from H‐Gln‐X‐OCH2‐resin was determined by a quantitative reaction, and found to be quite pronounced with X being Asn, Leu and Gly. The peptide‐resin with Leu was used to examine the influence of various reagents on the rate of pyroglutamate formation.