Structural Change of Keratin Protein in Human Hair by Permanent Waving Treatment

The study examined the structural damage to keratin protein in human hair caused by permanent waving treatment using various spectroscopic methods. It was found that the treatment led to a partial disruption of the α-helical structure in the hair's microfibrils, primarily during the initial reduction process. This disruption resulted in the α-helix changing to a random-coil structure rather than a β-sheet. The incomplete re-oxidation of disulphide bonds was previously considered the main cause of damage, but this study highlighted the significant role of structural changes in the microfibrils. The findings were supported by techniques such as 13C CP/MAS n.m.r., WAXD, FTi.r., and Raman spectroscopy.