Protein sulfhydryl group (PSH) (PSH)

Protein sulfhydryl groups, also known as protein thiols, are functional groups consisting of a sulfur atom and a hydrogen atom (-SH) attached to the amino acid cysteine within a protein structure (Source: UniProt). They play a critical role in maintaining protein conformation through the formation of disulfide bridges and are essential for the catalytic activity of many enzymes, such as cysteine proteases (Source: PubMed, PMID: 11356661). Beyond structural and enzymatic roles, these groups serve as vital components of the cellular antioxidant defense system, acting as "redox switches" that sense and respond to oxidative stress (Source: NIH, PMC3521968). In clinical practice, protein sulfhydryl groups are the primary targets for chelating agents used to treat heavy metal poisoning, such as lead, mercury, and arsenic, where the drugs bind to the thiols to prevent or reverse metal-induced toxicity (Source: StatPearls, NBK559112). Additionally, the high reactivity of the sulfhydryl group is exploited in the design of covalent inhibitors, which form permanent bonds with specific cysteine residues to achieve prolonged therapeutic effects in cancer and inflammatory diseases (Source: Nature Reviews Drug Discovery, 2022). Monitoring the levels of these groups in the blood can also serve as a biomarker for systemic oxidative stress and overall health status.

Other names

Protein thiolThiol groupCysteine sulfhydrylSulfhydryl moietyProtein-bound thiol

Chelation of heavy metals, restoration of redox balance, and covalent modification of specific cysteine residues.