Rhodanese, also known as rhodanase, thiosulfate sulfurtransferase, thiosulfate cyanide transsulfurase, and thiosulfate thiotransferase,
at the International Union of Biochemistry and Molecular Biology is a

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that detoxifies

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

(CN⁻) by converting it to

thiocyanate Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrot ...

(SCN⁻). This reaction takes place in two steps. The diagram on the right shows the crystallographically-determined structure of rhodanese. In the first step,

thiosulfate Thiosulfate ( IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, ...

is reduced by the

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

group on

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometime ...

-247 1, to form a

persulfide In chemistry, persulfide refers to the functional group R-S-S-H. Persulfides are intermediates in the biosynthesis of iron-sulfur proteins and are invoked as precursors to hydrogen sulfide, a signaling molecule. Nomenclature The nomenclature use ...

and a sulfite 2. In the second step, the persulfide reacts with cyanide to produce thiocyanate, re-generating the cysteine

1. This reaction is important for the treatment of exposure to cyanide, since the thiocyanate formed is around 1 / 200 as toxic.^:p. 15938 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 Rhodanese has an internal duplication. This domain is found as a single copy in other proteins, including phosphatases and ubiquitin C-terminal hydrolases.

Human proteins containing this domain

CDC25A M-phase inducer phosphatase 1 also known as dual specificity phosphatase Cdc25A is a protein that in humans is encoded by the cell division cycle 25 homolog A (CDC25A) gene. Function CDC25A is a member of the CDC25 family of dual-specificity ...

;

CDC25B M-phase inducer phosphatase 2 is an enzyme that in humans is encoded by the ''CDC25B'' gene. CDC25B is a member of the CDC25 family of phosphatases. CDC25B activates the cyclin dependent kinase CDC2 by removing two phosphate groups and it is requi ...

; CDC25C;

DUSP Dual-specificity phosphatase (DUSP; DSP) is a form of phosphatase that can act upon tyrosine or serine/ threonine residues. There are several families of dual-specificity phosphatase enzymes in mammals. All share a similar catalytic mechanism, b ...

;

DUSP1 Dual specificity protein phosphatase 1 is an enzyme that in humans is encoded by the ''DUSP1'' gene. Function The expression of DUSP1 gene is induced in human skin fibroblasts by oxidative/heat stress and growth factors. It specifies a protei ...

;

DUSP10 Dual specificity protein phosphatase 10 is an enzyme that in humans is encoded by the ''DUSP10'' gene. Dual specificity protein phosphatases inactivate their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine ...

;

DUSP16 Dual specificity protein phosphatase 16 is an enzyme that in humans is encoded by the ''DUSP16'' gene. The activation of mitogen-activated protein kinase (MAPK) cascades transduces various extracellular signals to the nucleus to induce gene expres ...

;

DUSP2 Dual specificity protein phosphatase 2 is an enzyme that in humans is encoded by the ''DUSP2'' gene. The protein encoded by this gene is a member of the dual specificity protein phosphatase subfamily. These phosphatases inactivate their target ...

;

DUSP4 Dual specificity protein phosphatase 4 is an enzyme that in humans is encoded by the ''DUSP4'' gene. Function The protein encoded by this gene is a member of the dual specificity protein phosphatase subfamily. These phosphatases inactivate th ...

;

DUSP5 Dual specificity protein phosphatase 5 is an enzyme that in humans is encoded by the ''DUSP5'' gene. Function The protein encoded by this gene is a member of the dual specificity protein phosphatase subfamily. These phosphatases inactivate th ...

;

DUSP6 Dual specificity phosphatase 6 (DUSP6) is an enzyme that in humans is encoded by the ''DUSP6'' gene. Function The protein encoded by this gene is a member of the dual specificity protein phosphatase subfamily. These phosphatases inactivate the ...

;

DUSP7 Dual specificity protein phosphatase 7 is an enzyme that in humans is encoded by the ''DUSP7'' gene. Function Dual-specificity phosphatases (DUSPs) constitute a large heterogeneous subgroup of the type I cysteine-based protein-tyrosine phosphat ...

; KAT; MKP7;

MOCS3 Adenylyltransferase and sulfurtransferase MOCS3 is an enzyme that in humans is encoded by the ''MOCS3'' gene. Molybdenum cofactor (MoCo) is necessary for the function of all molybdoenzymes. One of the enzymes required for the biosynthesis of MoCo ...

;

MPST In enzymology, a 3-mercaptopyruvate sulfurtransferase () is an enzyme that catalyzes the chemical reactions of 3-mercaptopyruvate. This enzyme belongs to the family of transferases, specifically the sulfurtransferases. This enzyme participates ...

; TBCK; TSGA14; TST;

USP8 Ubiquitin carboxyl-terminal hydrolase 8 is an enzyme that in humans is encoded by the ''USP8'' gene. Interactions USP8 has been shown to interact with RNF41 E3 ubiquitin-protein ligase NRDP1 is an enzyme that in humans is encoded by the ''RNF4 ...

;

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.

Thiosulfate sulfurtransferase

enzymology Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

, a thiosulfate sulfurtransferase () is an

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:thiosulfate + cyanide

\rightleftharpoons

sulfite + thiocyanate Thus, the two substrates of this enzyme are

and

, whereas its two

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

are

sulfite Sulfites or sulphites are compounds that contain the sulfite ion (or the sulfate(IV) ion, from its correct systematic name), . The sulfite ion is the conjugate base of bisulfite. Although its acid ( sulfurous acid) is elusive, its salts are wide ...

and

Nomenclature

This enzyme belongs to the family of

transferase A transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved in hundreds of di ...

s, specifically the sulfurtransferases, which transfer sulfur-containing groups. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

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

References

External links

* {{Portal bar, Biology, border=no EC 2.8 Protein domains