Extracellular disulfide-containing proteins on epithelial and mucosal surfaces

Extracellular disulfide-containing proteins on epithelial and mucosal surfaces represent a functional class of proteins, primarily mucins and viral attachment receptors, characterized by the presence of cysteine-mediated disulfide bridges (Thornton et al., 2008). These disulfide bonds are essential for the structural integrity and polymerization of mucins, which determine the viscoelastic properties of the protective mucus layer in the respiratory and gastrointestinal tracts. In pathological conditions such as cystic fibrosis and chronic obstructive pulmonary disease (COPD), oxidative stress leads to excessive disulfide cross-linking, resulting in hyperviscous mucus that is difficult to clear (Sadowska et al., 2006). Furthermore, many respiratory viruses, including SARS-CoV-2 and influenza, utilize disulfide-rich surface proteins to facilitate binding and entry into host cells (Hati & Bhattacharyya, 2020). Therapeutic intervention typically involves the use of thiol-based reducing agents, such as N-acetylcysteine, which cleave these disulfide bonds to reduce mucus viscosity and potentially disrupt viral infectivity (Aldini et al., 2018).

Other names

Mucus glycoproteinsCell-surface thiolsExtracellular disulfidesMucinsDisulfide-rich mucosal proteins

Reduction of extracellular disulfide bonds (S-S) to sulfhydryl groups (S-H), resulting in the cleavage of protein cross-links and reduction of macromolecular viscosity (Aldini et al., 2018).