Cellular proteins containing sulfur-bearing residues

Cellular proteins containing sulfur-bearing residues refer to a vast array of proteins that utilize the amino acids cysteine and methionine for structural and functional purposes. The sulfur atoms, particularly in the form of sulfhydryl (-SH) groups in cysteine, are essential for forming disulfide bonds that stabilize protein tertiary structure and for participating in redox reactions [1]. These residues are highly sensitive to oxidation and are primary targets for heavy metals like mercury, lead, and arsenic, which form stable mercaptides, thereby inactivating essential enzymes and transport proteins [2]. In toxicology and pharmacology, this group is often cited as the site of action for chelating agents like dimercaprol, which work by providing alternative sulfur-binding sites to sequester toxins away from cellular proteins [3]. Because this term describes a chemical characteristic shared by a significant portion of the proteome rather than a single entity, it is classified as a broad molecular category rather than a specific therapeutic target [4]. [1] https://doi.org/10.1093/jn/136.6.1636S [2] https://doi.org/10.1016/j.freeradbiomed.2017.01.015 [3] https://doi.org/10.3390/ijerph7072745 [4] https://doi.org/10.1016/j.freeradbiomed.2019.05.035

Other names

Sulfhydryl-containing proteinsThiol-containing proteinsCysteine-rich proteinsSulfur-containing proteins

Chelating agents compete with cellular sulfur-bearing residues for heavy metal ions to prevent or reverse protein inactivation, while electrophilic drugs or toxins covalently bind to sulfhydryl groups to inhibit protein function.