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

The study investigated the disulfide bond network within the wool fiber cortex, focusing on the accessibility of cysteines in trichocyte keratins and keratin-associated proteins (KAPs). By using staged labeling with reductants and chaotropic agents, researchers were able to expose and label cysteines, allowing for proteomic profiling 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. Additionally, cysteines in the rod domains of Types I and II keratins and in keratin head and tail domains were identified, suggesting their role in disulfide linkages. This research provided a deeper understanding of cysteine accessibility and reactivity in the wool fiber cortex.