Pyrrolid-2-One-5-Carboxylic Acid as an N-Terminal Group of the Low-Sulphur Proteins of Wool

Abstract

The detection of N-terminal pyrrolid-2-one-5-carboxylic acid (pyroglutamyl) residues in proteins is complicated by the ready formation of pyroglutamyl peptides from peptides with N-terminal glutaminyl residues which may be liberated during enzymic digestion of proteins. Recently, several methods for overcoming these problems have been described (Ikenaka et al. 1966; Wilkinson, Press, and Porter 1966; Doolittle and Armentrout 1968) and this communication describes the results obtained when two of these methods were applied to com~onent 8, one of the two major low-sulphur proteins extracted from reduced and carboxymethylated wool (Thompson and O'Donnell 1967)