Rhodanese

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Rhodanese-like domain
Rhodanase.png
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 is reduced by the thiol group on cysteine-247 1, to form a persulfide and a sulfite 2. In the second step, the persulfide reacts with cyanide to produce thiocyanate, re-generating the cysteine thiol 1.

Rhodanase2.png

This reaction is important for the treatment of exposure to cyanide, since the thiocyanate formed is less toxic.[medical citation needed] 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

  • Cdc25 phosphatase catalytic domain.
  • non-catalytic domains of eukaryotic dual-specificity MAPK-phosphatases
  • non-catalytic domains of yeast PTP-type MAPK-phosphatases
  • non-catalytic domains of yeast Ubp4, Ubp5, Ubp7
  • non-catalytic domains of mammalian Ubp-Y
  • Drosophila heat shock protein HSP-67BB
  • several bacterial cold-shock and phage shock proteins
  • plant senescence associated proteins
  • catalytic and non-catalytic domains of rhodanese (see <db_xref db="INTERPRO" dbkey="IPR001307" />).

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[edit]

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

Nomenclature[edit]

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[edit]

  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[edit]