Abstract: Wool keratin contains a large number of cysteine residues. The interaction between the sulfhydryl groups in these cysteine residues is important for maintaining the secondary and tertiary structure of the protein. In order to determine the sulfhydryl group content in wool keratin, the responsiveness of the sulfhydryl group by the 4,4'-dipyridyldisulfide (DPS) method and the classic Ellman's reagent method was compared in detail in different denaturants and pH systems. The study found that the DPS method had higher sulfhydryl responsiveness than the Ellman's reagent method at pH 7.0, 8 mol/L urea, 1% sodium dodecyl sulfate (SDS) and 3 mmol/L ethylenediamine tetraacetic acid (EDTA) buffer system. Therefore, the oxidation of sulfhydryl groups in wool keratin by hydrogen peroxide solution and the destruction of disulfide bonds in wool fiber protein by high temperature were verified by the DPS method in the above buffer system. The experimental results showed that the DPS method could be accurately and reliably applied to the determination of sulfhydryl content in wool keratin.
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