Structural changes in the trichocyte intermediate filaments accompanying the transition from the reduced to the oxidized form

The study re-examined previous data on trichocyte keratin intermediate filaments (IF) to provide a detailed understanding of structural changes during oxidation. It confirmed that newly assembled reduced IF fit an (8 + 0) model, with eight four-chain protofilaments arranged on an annular ring. However, oxidized IF required a (7 + 1) model due to a periodic imperfection in the surface lattice. The study also found that oxidation leads to lateral compaction and disruption of local coiled-coil geometry near cysteine residues, consistent with X-ray diffraction patterns. These findings were supported by X-ray and cryo-electron microscopy data, offering insights into the molecular reorganization during the transition from a reducing to an oxidizing environment.