The Susceptibility of Disulfide Bonds to Modification in Keratin Fibers Undergoing Tensile Stress

The study examines how tensile stress affects disulfide bonds in keratin fibers, using wool from Romney sheep. It finds that certain cysteine residues in keratin proteins are more prone to breaking under stress, with susceptibility varying based on the fiber's water content. In wet conditions, disulfide bonds in the head domains of type II keratins and tail domains of type I keratins are more affected, impacting keratin-keratin and keratin-keratin-associated protein interactions. In dry conditions, disulfide bonds in the central domains are also affected. The study suggests that the location of disulfide bonds within the keratin structure influences their mechanical contribution, with water content playing a significant role. The research highlights the importance of specific cysteine residues in keratin-KAP interactions during early follicle development, particularly involving K85 and KAP11.1.