Thiol- and imidazole-containing proteins

Thiol- and imidazole-containing proteins represent a broad functional class of biological molecules characterized by the presence of nucleophilic cysteine (thiol) and histidine (imidazole) residues. These residues are frequently located within the active or regulatory sites of enzymes, where they participate in critical processes such as redox signaling, catalysis, and structural stabilization. In a therapeutic context, this group is recognized as the primary target for gold-based antirheumatic drugs like auranofin and gold sodium thiomalate, which exert their effects by covalently binding to these sulfur and nitrogen donors. By modifying these proteins, such drugs can inhibit key inflammatory mediators and enzymes like thioredoxin reductase, thereby modulating immune responses and inducing apoptosis in malignant cells. However, because these chemical groups are ubiquitous across the proteome, drugs targeting them often face challenges related to systemic toxicity and a lack of molecular specificity.

Other names

Thiol-containing proteinsImidazole-containing proteinsSulfhydryl-containing proteinsCysteine- and histidine-containing proteins

Drugs, particularly gold-based compounds, act as soft electrophiles that form covalent bonds with the nucleophilic sulfur atoms of thiol groups (cysteine residues) and nitrogen atoms of imidazole groups (histidine residues) within various proteins. This interaction often leads to the irreversible inhibition of enzymes involved in redox homeostasis and inflammatory signaling.