Action of Nucleophilic Reagents on Hair Keratin

The study investigated the degradation of cystine bonds in hair keratin by nucleophilic reagents, including alkylamines, amines with aromatic rings, amino acids, and amine-thiol combinations, under high alkalinity (pH 13) and moderate temperature (40 °C). It was found that the alkaline degradation of hair followed a mechanism similar to wool, leading to the formation of dehydroalanine residues via β-elimination. These residues reacted further with amino and thiol groups to produce lysinoalanine, lanthionine, and β-(N-alkylamino)alanines. Although the degradation pathways in hair were similar to wool, the relative ratios of reaction products differed, with less amine adduct and more lanthionine and lysinoalanine residues formed under the study's conditions.