Cross-Linkage Formation in Keratin

Abstract

WHEN animal fibres, such as wool and hair, are treated with an acid solution of 3 : 4-isopropylidene 1 : 2-5 : 6-dianhydromannitol for 24 hr. at 50° C., cross-linkages are formed between the carboxyl groups of neighbouring peptide chains¹. Since the fibres are then more resistant to deformation, their felting power is reduced, and attention has therefore been turned to the possibility of cross-linking wool with simpler di-epoxides, for example, 1 : 2-3 : 4-diepoxybutane (I) and 1 : 2-5 : 6-diepoxyhexane (II). For this purpose, Lincoln wool fibres were purified by extraction with alcohol and ether, washed in distilled water, and then treated for 24 hr. at 50° C. with a 2.5 per cent solution of the di-epoxide in a phosphate buffer at the appropriate pH. After being washed in running water for 24 hr., the fibres were examined for the presence of new cross-linkages by determining the extent to which supercontraction could be induced by boiling for 30 min. in a 5 percent solution of sodium metabisulphite². The results are given in the accompanying table.