Mapping the Accessibility of the Disulfide Crosslink Network in the Wool Fiber Cortex

The study investigated the disulfide bond network within the cortex of wool fibers, focusing on the accessibility and reactivity of cysteine residues in trichocyte keratins and keratin-associated proteins (KAPs). By using staged labeling with reductants and chaotropic agents, researchers exposed and labeled cysteines to map peptide modifications. The findings revealed that cysteines in the end domains of KAPs were easily accessible and potentially involved in forming interdisulfide linkages with keratins or other KAPs. Additionally, cysteines from the rod domains of Types I and II keratins and from keratin head and tail domains were identified, suggesting their role in forming disulfide linkages. This research provided a deeper understanding of the disulfide crosslink network in wool fibers.