Rhodanese

Rhodanese-like domain
Identifiers
Symbol Rhodanese
Pfam PF00581
InterPro IPR001763
PROSITE PDOC00322
SCOP 2ora
SUPERFAMILY 2ora

Rhodanese, also known as rhodanase, thiosulfate sulfurtransferase, thiosulfate cyanide transsulfurase, and thiosulfate thiotransferase,[1] is a mitochondrial enzyme that detoxifies cyanide (CN) by converting it to thiocyanate (SCN).[2]

This reaction takes place in two steps. The diagram on the right shows the crystallographically-determined structure of rhodanese. In the first step, thiosulfate reacts with the thiol group on cysteine-247 1, to form a persulfide 2. In the second step, the disulfide reacts with cyanide to produce thiocyanate, itself being converted back into the "normal" thiol 1.

This reaction is important for the treatment of exposure to cyanide, since the thiocyanate formed is less toxic. The use of thiosulfate solution as an antidote for cyanide poisoning is based on the activation of this enzymatic cycle.

Rhodanese shares evolutionary relationship with a large family of proteins, including

Rhodanese has an internal duplication. This domain is found as a single copy in other proteins, including phosphatases and ubiquitin C-terminal hydrolases.[3]

Human proteins containing this domain

CDC25A; CDC25B; CDC25C; DUSP; DUSP1; DUSP10; DUSP16; DUSP2; DUSP4; DUSP5; DUSP6; DUSP7; KAT; MKP7; MOCS3; MPST; TBCK; TSGA14; TST; USP8;

Nomenclature

Although the standard nomenclature rules for enzymes indicate that their names are to end with the letters "-ase", rhodanese was first described in 1933,[4] prior to the 1955 establishment of the Enzyme Commission; as such, the older name had already attained widespread usage.

References

  1. EC 2.8.1.1, at the International Union of Biochemistry and Molecular Biology
  2. Cipollone R, Ascenzi P, Tomao P, Imperi F, Visca P (2008). "Enzymatic detoxification of cyanide: clues from Pseudomonas aeruginosa Rhodanese". J. Mol. Microbiol. Biotechnol. 15 (2-3): 199–211. doi:10.1159/000121331. PMID 18685272.
  3. Gliubich F, Gazerro M, Zanotti G, Delbono S, Bombieri G, Berni R (1996). "Active site structural features for chemically modified forms of rhodanese". J. Biol. Chem. 271 (35): 21054–21061. doi:10.1074/jbc.271.35.21054. PMID 8702871.
  4. Common Themes and Variations in the Rhodanese Superfamily, by Rita Cipollone, Paolo Ascenzi, and Paolo Visca, in IUBMB Life, vol. 59, no. 2 (February 2007); page 51-59; DOI: 10.1080/15216540701206859

External links

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