The role of disulfide bond formation in the structural transition observed in the intermediate filaments of developing hair

The study explored the role of disulfide bond formation in the structural transition of intermediate filaments (IF) in developing hair. It was found that during hair keratinization, the redox environment changes, leading to the oxidation of cysteine residues and the formation of disulfide bonds. This structural transition involved molecular slippage and radial compaction, with disulfide bonds playing a crucial role due to their high energy compared to hydrogen bonds or van der Waals interactions. The study improved the precision of molecular parameter values in oxidized fibers, supporting the idea that the decrease in free energy from disulfide bond formation is a primary factor in the axial arrangement of molecules in oxidized hard α-keratins. The findings suggested that the slippage observed in trichocyte IF during keratinization did not occur in epidermal IF.