Thiosulfate sulfurtransferase (TST)

Thiosulfate sulfurtransferase (TST), commonly known as rhodanese, is a mitochondrial enzyme comprising about 300 amino acids that detoxifies cyanide by transferring a sulfur atom from thiosulfate to cyanide, generating thiocyanate and sulfite. The enzyme is structurally characterized by the rhodanese fold, an α/β sandwich seen in both catalytically active and inactive sulfurtransferase family members. Rhodanese plays diverse biological roles, including cyanide detoxification, iron–sulfur cluster assembly, selenium metabolism, and participation in the biosynthesis of cofactors such as thiamine. The enzyme cycles between a sulfur-free and a persulfide (sulfur-bound) intermediate state during catalysis, with the catalytic cysteine residue (commonly Cys-247) being essential for activity. Thiosulfate is the best characterized exogenous donor for the reaction. The rhodanese domain is present in a broad range of proteins, and variants lacking catalytic activity may act in regulatory or structural roles. Clinically, thiosulfate sulfurtransferase is relevant in cyanide intoxication, where its activity (endogenous and pharmacologically augmented by sodium thiosulfate) provides a critical detoxification pathway[1][5][3][8].

Other names

thiosulfate cyanide transsulfurasethiosulfate thiotransferaserhodaneserhodanase

Detoxifies cyanide by catalyzing conversion of cyanide to thiocyanate using thiosulfate as a sulfur donor; forms enzyme–sulfur intermediates in a double displacement reaction; produces sulfite and thiocyanate as products[1][3][5]