Protein disulfide bonds in keratin and extracellular matrix proteins

Protein disulfide bonds are covalent cross-links formed between the thiol groups of cysteine residues, playing a critical role in the structural stabilization of keratin and various extracellular matrix (ECM) proteins (NCBI, 2015). In keratins, these bonds are responsible for the mechanical strength and rigidity of hair, skin, and nails, while in the ECM, they facilitate the assembly and stability of complex networks like the basement membrane (UniProt, 2023). These bonds are primary targets for chemical agents in both cosmetic and therapeutic applications; for instance, reducing agents like thioglycolates are used to break disulfide bridges in hair for reshaping, and mucolytics like N-acetylcysteine target these bonds to reduce the viscosity of mucus (PubChem, 2024; StatPearls, 2023). Disruptions in disulfide bond formation or maintenance are associated with various genetic disorders, including keratinopathies and connective tissue diseases (PubMed, 2005). Understanding the dynamics of these bonds is essential for developing treatments for conditions characterized by abnormal protein cross-linking or for enhancing drug delivery through keratinous barriers (PMC, 2019).

Other names

Cystine bridgesDisulfide cross-linksS-S bondsDisulfide bridges

Reduction of covalent disulfide (S-S) bridges into free sulfhydryl (-SH) groups via thiol-disulfide exchange, leading to the denaturation, structural softening, or increased solubility of the protein matrix.