Protein thiol groups on bacterial and mucosal proteins (Protein-SH)

Protein thiol groups, specifically the sulfhydryl (-SH) side chains of cysteine residues, are critical molecular targets for a variety of antimicrobial and antiseptic agents (Source: Lansdown, 2002, Journal of Wound Care). These groups are essential for the structural integrity and catalytic activity of numerous bacterial enzymes, including those involved in the respiratory chain and cell wall synthesis (Source: Jung et al., 2008, Applied and Environmental Microbiology). When targeted by heavy metal ions such as silver (Ag+), the thiols undergo coordination or covalent modification, forming stable mercaptides that result in widespread protein denaturation and rapid bactericidal action (Source: StatPearls, Silver Nitrate). On mucosal surfaces, the interaction with host protein thiols can facilitate the formation of a protective proteinaceous barrier or exert an astringent effect, which is utilized in the treatment of localized infections and inflammatory conditions (Source: Goodman & Gilman's The Pharmacological Basis of Therapeutics). However, the lack of high selectivity between bacterial and host thiols necessitates careful dosing and localized application to avoid adverse effects such as argyria or impaired tissue regeneration (Source: DrugBank, Silver Sulfadiazine). This broad-spectrum mechanism of action makes it difficult for bacteria to develop resistance, as multiple essential proteins are affected simultaneously.

Other names

Sulfhydryl groupsCysteine thiolsProtein sulfhydrylsMercaptan groupsProtein-SHBacterial protein thiolsMucosal protein thiolsProtein-bound sulfhydryl groups

The mechanism of action involves the high-affinity binding of metal ions or electrophiles to the sulfur atom of protein thiol groups. This interaction leads to the formation of stable mercaptides or the oxidation of thiols to disulfides, which causes the structural denaturation of essential bacterial enzymes (e.g., NADH dehydrogenase) and structural proteins, disrupting cellular respiration and membrane integrity (Source: Jung et al., 2008; Lansdown, 2002). On mucosal tissues, this binding results in an astringent effect by precipitating surface proteins.