Information on EC 1.8.2.5 - thiosulfate reductase (cytochrome)

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.8.2.5
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RECOMMENDED NAME
GeneOntology No.
thiosulfate reductase (cytochrome)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
sulfite + hydrogen sulfide + 2 ferricytochrome c3 = thiosulfate + 2 ferrocytochrome c3
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
thiosulfate disproportionation II (cytochrome)
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SYSTEMATIC NAME
IUBMB Comments
sulfite,hydrogen sulfide:ferricytochrome-c3 oxidoreductase (thiosulfate-forming)
The enzyme is found in sulfate-reducing bacteria. The source of the electrons is molecular hydrogen, via EC 1.12.2.1, cytochrome-c3 hydrogenase. The organisms utilize the sulfite that is produced for energy generation by EC 1.8.99.5, dissimilatory sulfite reductase.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
sulfate-reducing bacteria
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Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
thiosulfate + 2 ferrocytochrome c3
sulfite + hydrogen sulfide + 2 ferricytochrome c3
show the reaction diagram
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?
thiosulfate + reduced benzyl viologen
sulfite + hydrogen sulfide + oxidized benzyl viologen
show the reaction diagram
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about 50% of the rate with methyl viologen
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?
thiosulfate + reduced methyl viologen
sulfite + hydrogen sulfide + oxidized methyl viologen
show the reaction diagram
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
thiosulfate + 2 ferrocytochrome c3
sulfite + hydrogen sulfide + 2 ferricytochrome c3
show the reaction diagram
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
cytochrome c
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presence of a cytochrome that may be an intermediary hydrogen carrier involved in reducing systems for sulfate and other sulfur compounds
cytochrome c3
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
4-chloromercuribenzoate
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0.02 mM, 100% inhibition. Inhibition can be partially or completely reversed by cysteine
4-hydroxymercuribenzoate
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activity can be restored by cysteine
Ag+
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0.01 mM, 90% inhibition
Hg2+
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0.01 mM, 100% inhibition
iodoacetate
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0.5 mM, 70% inhibition
N-ethylmaleimide
o-Iodosobenzoate
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0.05 mM, 52% inhibition
sulfite
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.5
thiosulfate
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37°C, pH 7.6
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
41
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37°C, pH 7.6
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.8
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8% of maximum activity
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
16300
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sedimentation equilibrium centrifugation
220000
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gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
monomer
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1 * 15500, amino acid analysis
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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presence of two half-cystine residues per mole of enzyme
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
three-dimensional structure of the fusion protein with electron-transferring protein TsdB, to 2.75 A resolution. In the oxidized state, the tetraheme cytochrome c contains three hemes with axial His/Met ligation, whereas heme 3 exhibits the His/Cys coordination typical for TsdA active sites. Thiosulfate is covalently bound to Cys330 on heme 3
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
enzyme loses activtiy upon freezing and thawing
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-20°C, 33% loss of activity within 2 weeks
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-20°C, lyophilized preparation, stable for at least 1 month
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
unstable during purification
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