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

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Abstract
Wool has been reduced and extracted by urea-mercaptoethanol solution and the cysteine residues labelled by carboxymethylation with 2-[C14]iodoacetate. The extracted protein has been fractionated into the 3 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 3 fractions were almost identical in the peptides obtained, althouhg marked differences in intensities were apparent. However, radioautographs of peptide maps of tryptic digests of the 3 fractions showed marked differences in the peptide patterns obtained. The findings are discussed in relation to the structure and synthesis of wool.