Epidermal keratin and protein disulfide bonds

Epidermal keratins are fibrous structural proteins that constitute the primary component of the intermediate filament cytoskeleton in epithelial cells, providing essential mechanical stability and barrier function to the skin (UniProt, P13645; NIH, NBK560714). These proteins are characterized by a high content of cysteine residues, which form extensive intra- and intermolecular disulfide bonds that cross-link the keratin filaments into a dense, resilient matrix (Journal of Investigative Dermatology, 2015). In the stratum corneum, this keratinized structure is vital for protecting the body against environmental stressors, pathogens, and dehydration (StatPearls, NBK560714). From a therapeutic perspective, these proteins and their stabilizing disulfide bonds are targeted by two main classes of agents: keratolytics and depilatories (PubChem, CID 1133). Keratolytic agents, such as salicylic acid and high-concentration urea, work by disrupting the hydrogen bonds and intercellular adhesion within the keratin matrix to promote the shedding of dead skin cells in conditions like psoriasis and hyperkeratosis (StatPearls, NBK560714). Conversely, depilatory agents like thioglycolic acid salts target the disulfide bonds directly, reducing them to thiol groups, which weakens the hair's structural integrity and allows for its mechanical removal (PubChem, CID 1133). Understanding the biochemical properties of these bonds is crucial for developing treatments that balance efficacy in protein degradation with the maintenance of skin health.

Other names

KeratinCytokeratinDisulfide bridgesCystine bondsIntermediate filamentsKRT

Chemical reduction of disulfide bonds to destabilize protein structure (depilatories) or disruption of hydrogen bonding and intercellular adhesion to facilitate desquamation (keratolytics).