The Hydrothermal Degrádation of Wool Keratin

Abstract

The nature of degradation of cystyl residues in wool by purified water at ca. pH 6 and at temperatures of 50-100° is studied. Cystyl residues in wool are slowly converted by water to lanthionyl residues, even at 60°, and the rate of this conversion increases with increasing temperature. At 100°, lanthionyl residues cannot form in solutions having pH values below ca. 4.5-5.0. Evidence suggests that, under these conditions, certain reactive sulfur-containing residues are also formed from cystyl residues. The other major action of water on wool at 100° appears to be in the hydrolysis of certain peptide bonds. Limited modification of residues in wool, such as the lysyl and tyrosyl, also apparently occurs during treatment of wool with water at 100°. Comparison of the amino-acid contents of the water extracts obtained at 100° and those of the treated wool samples reveals that some residues are either more or less easily extracted from wool than others.