The Influence of Electrode Potentials on the Extent of Reduction of Cystine in Hair Fibers by Reducing Agents

The study examined how the electrode potentials of reducing agents affect the reduction of cystine disulfide linkages in hair fibers. Using a tensiometer, researchers measured the relaxation of hair fibers in various reducing solutions and found that the extent of reduction, indicated by equilibrium stress levels, depended on the electrode potential of the reducing agent. Chemical analyses confirmed that stress reduction corresponded to cystine disulfide linkage reduction. The results suggest that cystine residues in keratin fibers have different standard electrode potentials, and the reduction is influenced by the potential of the reducing agents rather than pH or ionic strength.