Rhodanese - Misplaced Pages

Rhodanese is a mitochondrial enzyme that detoxifies cyanide (CN) by converting it to thiocyanate (SCN, also known as "rhodanate"). In enzymatology, the common name is listed as thiosulfate sulfurtransferase (EC 2.8.1.1). The diagram on the right shows the crystallographically-determined structure of rhodanese.

It catalyzes the following reaction:

thiosulfate + cyanide

\rightleftharpoons

sulfite + thiocyanate

Structure and mechanism

This reaction takes place in two steps. 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.

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

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

Clinical relevance

This reaction is important for the treatment of exposure to cyanide, since the thiocyanate formed is around 1 / 200 as toxic. The use of thiosulfate solution as an antidote for cyanide poisoning is based on the activation of this enzymatic cycle.

Human proteins

The human mitochondrial rhodanese gene is TST.

The following other human genes match the "Rhodanese-like" domain on InterPro, but are not the rodanase with its catalytic activity (see also the list of related families in #Structure and mechanism):

M-phase inducer phosphatase: CDC25A; CDC25B; CDC25C;
Dual specificity protein phosphatase: DUSP; DUSP1; DUSP2; DUSP4; DUSP5; DUSP6; DUSP7; DUSP10; DUSP16, aka MKP7;
Thiosulfate:glutathione sulfurtransferase: KAT, now known as "TSTD1";
Adenylyltransferase and sulfurtransferase: MOCS3;
3-mercaptopyruvate sulfurtransferase: MPST, also known as "TSTD2"
Not an enzyme: TBCK; TSGA14;
Ubiquitin carboxyl-terminal hydrolase: USP8;
Unknown activity: TSTD3

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, prior to the 1955 establishment of the Enzyme Commission; as such, the older name had already attained widespread usage.

The systematic name of this enzyme class is "thiosulfate:cyanide sulfurtransferase". Other names in common use include "thiosulfate cyanide transsulfurase", "thiosulfate thiotransferase", "rhodanese", and "rhodanase".

References

Cipollone R, Ascenzi P, Tomao P, Imperi F, Visca P (2008). "Enzymatic detoxification of cyanide: clues from Pseudomonas aeruginosa Rhodanese". Journal of Molecular Microbiology and Biotechnology. 15 (2–3): 199–211. doi:10.1159/000121331. PMID 18685272. S2CID 25431686.
EC 2.8.1.1, at the International Union of Biochemistry and Molecular Biology
Cipollone R, Ascenzi P, Tomao P, Imperi F, Visca P (2008). "Enzymatic detoxification of cyanide: clues from Pseudomonas aeruginosa Rhodanese". Journal of Molecular Microbiology and Biotechnology. 15 (2–3): 199–211. doi:10.1159/000121331. PMID 18685272. S2CID 25431686.
"Thiosulphate sulfurtransferase, conserved site (IPR001307)". EMBL-EBI. InterPro.
Gliubich F, Gazerro M, Zanotti G, Delbono S, Bombieri G, Berni R (August 1996). "Active site structural features for chemically modified forms of rhodanese". The Journal of Biological Chemistry. 271 (35): 21054–61. doi:10.1074/jbc.271.35.21054. PMID 8702871.
Jaszczak E, Polkowska Ż, Narkowicz S, Namieśnik J (July 2017). "Cyanides in the environment-analysis-problems and challenges". Environmental Science and Pollution Research International. 24 (19): 15929–15948. doi:10.1007/s11356-017-9081-7. PMC 5506515. PMID 28512706.
Cipollone R, Ascenzi P, Visca P (February 2007). "Common themes and variations in the rhodanese superfamily". IUBMB Life. 59 (2): 51–9. doi:10.1080/15216540701206859. PMID 17454295.

External links

Rhodanese at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

v t e Transferases: sulfur-containing group (EC 2.8)
2.8.1: Sulfurtransferases	Thiosulfate sulfurtransferase Rhodanese 3-mercaptopyruvate sulfurtransferase thiosulfate—thiol sulfurtransferase tRNA sulfurtransferase thiosulfate—dithiol sulfurtransferase biotin synthase cysteine desulfurase lipoyl synthase molybdenum cofactor sulfurtransferase thiazole synthase molybdopterin synthase sulfurtransferase molybdopterin synthase tRNA-uridine 2-sulfurtransferase () tRNA-5-taurinomethyluridine 2-sulfurtransferase () tRNA-5-methyluridine 2-sulfurtransferase () L-aspartate semialdehyde sulfurtransferase ()
2.8.2: Sulfotransferases	aryl sulfotransferase amine sulfotransferase estrone sulfotransferase chondroitin 4-sulfotransferase choline sulfotransferase UDP-N-acetylgalactosamine-4-sulfate sulfotransferase heparan sulfate-glucosamine N-sulfotransferase tyrosine-ester sulfotransferase Renilla-luciferin sulfotransferase galactosylceramide sulfotransferase psychosine sulfotransferase bile salt sulfotransferase steroid sulfotransferase thiol sulfotransferase chondroitin 6-sulfotransferase cortisol sulfotransferase triglucosylalkylacylglycerol sulfotransferase protein-tyrosine sulfotransferase keratan sulfotransferase aryl-sulfate sulfotransferase (heparan sulfate)-glucosamine 3-sulfotransferase 1 desulfoglucosinolate sulfotransferase flavonol 3-sulfotransferase quercetin-3-sulfate 3′-sulfotransferase quercetin-3-sulfate 4′-sulfotransferase quercetin-3,3′-bissulfate 7-sulfotransferase (heparan sulfate)-glucosamine 3-sulfotransferase 2 (heparan sulfate)-glucosamine 3-sulfotransferase 3 petromyzonol sulfotransferase scymnol sulfotransferase N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase glycochenodeoxycholate sulfotransferase dermatan 4-sulfotransferase desulfo-A47934 sulfotransferase () trehalose 2-sulfotransferase () aliphatic desulfoglucosinolate sulfotransferase () hydroxyjasmonate sulfotransferase () ω-hydroxy-β-dihydromenaquinone-9 sulfotransferase (*) Alcohol sulfotransferase Tyrosylprotein sulfotransferase
2.8.3: CoA-transferases	Propionate CoA-transferase oxalate CoA-transferase malonate CoA-transferase 3-oxoacid CoA-transferase 3-oxoadipate CoA-transferase succinyl-CoA—Dcitramalate CoA-transferase acetate CoA-transferase butyrate—acetoacetate CoA-transferase citrate CoA-transferase citramalate CoA-transferase glutaconate CoA-transferase succinate—hydroxymethylglutarate CoA-transferase 5-hydroxypentanoate CoA-transferase succinyl-CoA:(R)-benzylsuccinate CoA-transferase formyl-CoA transferase cinnamoyl-CoA:phenyllactate CoA-transferase succinyl-CoA:acetate CoA-transferase () CoA:oxalate CoA-transferase () succinyl-CoA—D-citramalate CoA-transferase () L-carnitine CoA-transferase () succinyl-CoA—L-malate CoA-transferase () caffeate CoA-transferase () (R)-2-hydroxy-4-methylpentanoate CoA-transferase () bile acid CoA-transferase () succinyl-CoA:mesaconate CoA transferase (*)
2.8.4: Alkylthio	2.8.4: Coenzyme-B sulfoethylthiotransferase arsenate-mycothiol transferase tRNA-2-methylthio-N-dimethylallyladenosine synthase () (aspartate-C)-methylthiotransferase () tRNA (N-L-threonylcarbamoyladenosine-C)-methylthiotransferase (*)
2.8.5:	2.8.5: S-sulfo-L-cysteine synthase (3-phospho-L-serine-dependent) () L-cysteine S-thiosulfotransferase ()

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

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