Microbial sulfhydryl group (-SH)

Microbial sulfhydryl groups, also known as thiol groups (-SH), are essential chemical moieties found on the cysteine residues of numerous proteins in bacteria, fungi, and viruses. These groups are critical for microbial survival as they participate in the formation of disulfide bridges that maintain protein structure and serve as active sites for many metabolic enzymes (Lemire et al., 2013). Various antimicrobial agents, including heavy metals like silver and mercury, as well as oxidizing antiseptics, exert their microbicidal effects by reacting with these sulfhydryl groups. This interaction typically results in the formation of stable mercaptides or the oxidation of thiols, which inactivates the target proteins and disrupts essential cellular processes such as respiration and DNA replication (McDonnell & Russell, 1999). While highly effective as broad-spectrum disinfectants and topical treatments (e.g., silver sulfadiazine for burns), their therapeutic use is often limited by a lack of specificity, as they can also react with sulfhydryl groups in human host proteins, potentially leading to systemic toxicity (StatPearls, 2023).

Other names

Thiol groupSulfhydryl moietyProtein thiolMercapto group

Antimicrobial agents target microbial sulfhydryl groups through covalent binding (mercaptide formation), oxidation to disulfide bonds, or alkylation, which leads to the inactivation of essential enzymes and the denaturation of structural proteins (McDonnell & Russell, 1999; Lemire et al., 2013).