Microbial thiol-containing residues (-SH groups)

Microbial thiol-containing residues, primarily the sulfhydryl (-SH) groups found on cysteine amino acids, are essential functional components of numerous bacterial, fungal, and viral proteins. These residues are critical for maintaining the tertiary structure of proteins through disulfide bridge formation and are often found within the active sites of metabolic enzymes, such as dehydrogenases, where they facilitate catalysis (McDonnell & Russell, 1999, Clinical Microbiology Reviews). Additionally, thiols play a central role in microbial redox homeostasis, protecting cells from oxidative stress through molecules like glutathione or mycothiol (Slavin et al., 2017, Journal of Nanobiotechnology). Many broad-spectrum antiseptics and disinfectants exploit the high reactivity of these groups; for instance, silver ions (Ag+) have a high affinity for thiols, binding to them to cause immediate protein dysfunction and cell death (Finnegan & Percival, 2015, Journal of Wound Care). Oxidizing agents like povidone-iodine also target these residues, converting them into inactive forms and disrupting the microbial cell membrane and internal machinery (Bigliardi et al., 2017, International Journal of Surgery). While highly effective as topical treatments, the therapeutic challenge lies in the potential for these agents to also react with host thiol groups, necessitating careful concentration management to avoid cytotoxicity.

Other names

Sulfhydryl groupsThiol groupsProtein thiolsCysteine residuesMicrobial sulfhydryl groups

Antimicrobial agents target these residues through covalent binding (mercaptide formation with heavy metals) or oxidation (conversion of thiols to disulfides or sulfenic/sulfonic acids), leading to protein denaturation and enzyme inactivation.