Studies on Reduced Wool VI. Comparison of Peptides Containing S-Carboxymethylcysteinyl Residues in Different Protein Fractions

Abstract

Wool has been reduced and extracted by urea-mercaptoethanol solution and the cysteine residues labelled by carboxymethylation with 2-[14C]iodoacetate. The extracted protein has been fractionated into the three main classes of protein present in wool, namely the high-sulphur, low-sulphur, and high-glycine-high-aromatic amino acid fractions. After partial acid hydrolysis of each fraction, peptide maps were prepared by paper ionophoretic and chromatographic methods and the S-carboxymethyl- containing peptides located by radioautography. The peptide maps given by the three fractions were almost identical in the peptides obtained, although marked differences in intensities were apparent. However, radioautographs of peptide maps of tryptic digests of the three fractions showed marked differences in the peptide patterns obtained. The findings are discussed in relation to the structure and synthesis of wool.