Abstract
In the cosmetic industry, various keratin proteins have been applied for the protection from hair damage and the restoration of damaged hair. The water-soluble S-carboxymethylalanyl disulfide keratin ( CMADK) protein including the unsymmetrical disulfide groups was synthesized by reduction treatment of wool fiber with sodium thioglycolate and subsequent oxidation with hydrogen peroxide. In an SDS-PAGE method, major bands of 64 kDa and 48 kDa were commonly observed in the newly derivatized protein. The amount of disulfide groups in the protein was analyzed to be 4.4×10-4 mol/g of protein. The modification of the hair surface with the soluble CMADK protein by covalent SS bonding was expected through the SH/SS interchange reaction between the unsymmetrical disulfide group in the protein and the free thiol group in the hair. The modulus of rigidity based on torsion stress of the hair treated with CMADK protein was increased, and the increased modulus was maintained during the shampooing performed by using a simulation model.
