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Overview for MACiE Entry M0284

Version history

General Information

EC Number: 3.5.5.8 (A member of the Hydrolases, Acting on carbon-nitrogen bonds, other than peptide bonds, In nitriles)

Enzyme Name: thiocyanate hydrolase

Biological Species: Thiobacillus thioparus (Bacteria)

Catalytic Chain UniprotKB Accession Codes:

  • O66188 - Thiocyanate hydrolase subunit gamma

Representative PDB Code: 2dd5 - THIOCYANATE HYDROLASE (SCNASE) FROM THIOBACILLUS THIOPARUSNATIVE HOLO-ENZYME (Resolution = 2.00 Å).

Catalytic CATH Codes:

"Other" CATH Codes:

Display structure information

Overall Reaction:

Image of thiocyanate

Image of water

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Image of hydroxide anion

Image of carbonyl sulfide

Image of ammonia

thiocyanate
C01755
CHEBI:29200
2 water
C00001
CHEBI:15377
hydroxide anion
C01328
CHEBI:16234
carbonyl sulfide
C07331
CHEBI:16573
ammonia
C00014
CHEBI:16134

Overall Comment: Thiocyanate hydrolase catalyses the degradation of thiocyanate to carbonyl sulfide and ammonia. An alternative mechanism, involving enzyme-substrate covalent intermediates has been suggested, although no evidence is available to support the existence of such species [2]. Structural studies show all three chains to surround the active site, with positive side chains projecting towards the metal centre from each of them, stabilising the negatively charged substrate and product [1].


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Stepwise Description of the Reaction

Step 1Tyr108 activates a water molecule towards nucleophilic attack on the Co(III) coordinated thiocyanate substrate.
Step 2A proton is exchanged between the hydrolysis product and Tyr108C.
Step 3Tautomerisation of the intermediate results in a carbonyl species.
Step 4An internal proton transfer occurs.
Step 5The hydroxyl present on Cys133 activates a water molecule to act as a nucleophile towards the thio-acid intermediate.
Step 6The tetrahedral anion collapses resulting in concomitant release of ammonia and deprotonation of Cys133.
Step 7An intermolecular elimination of hydroxide occurs, forming carbonyl sulfide.

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Catalytic Residues Involved

Type Number Chain Location of Function
Cso 133 C Main Chain Amide
Post-translationally modified residue
Tyr 108 C Side Chain
Ser 132 C Side Chain
Main Chain Amide
Csd 131 C Post-translationally modified residue
Cys 128 C Side Chain

Metal Cofactors for M0284

Type Het group Number Chain
cobalt 3CO 301 C Overview

References

  1. T. Arakawa et al. (2007), J. Mol. Biol., 366, 1497-1509. Structure of thiocyanate hydrolase: a new nitrile hydratase family protein with a novel five-coordinate cobalt(III) center.
    Medline: 17222425
  2. N. Gupta et al. (0), J. Hazard Mater., 176, 1-13. .
    Medline: 20004515
  3. T. Arakawa et al. (2009), J. Am. Chem. Soc., 131, 4838-4843. Structural Basis for Catalytic Activation of Thiocyanate Hydrolase Involving Metal-Ligated Cysteine Modification.
    Medline: 19785438
  4. Y. Katayama et al. (1998), J. Bacteriol., 180, 2583-2589. Cloning of genes coding for the three subunits of thiocyanate hydrolase of Thiobacillus thioparus THI 115 and their evolutionary relationships to nitrile hydratase.
    Medline: 9573140

Homologue information for M0284 (2dd5)

CSA Homologues

MACiE Homologues (within the PDB)

MACiE Homologues (within UniprotKB/SwissProt)


Links to this entry in other databases

Link to EC-PDB-SUM Link to PDB-SUM Link to RCSB PDB Link to PDBe Link to CSA
Link to MetaCyc Link to KEGG Link to BRENDA Link to ExplorENZ

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catalytic activity (molecular function)
nitrogen compound metabolic process (biological process)
plastid (cellular component)
photosynthesis (biological process)
hydrolase activity (molecular function)
thiocyanate hydrolase activity (molecular function)
metal ion binding (molecular function)
transition metal ion binding (molecular function)
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