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Enzyme Nomenclature
Information on EC 1.8.5.4 - bacterial sulfide:quinone reductase
for references in articles please use BRENDA:EC1.8.5.4
Word Map on EC 1.8.5.4
- 1.8.5.4
- sulfur
- h2s
- thiosulfate
- persulfide
- rhodanese
-
polysulfide
- acidithiobacillus
- ferrooxidans
-
sulfurtransferase
-
sulfide-dependent
-
chemolithotrophic
- tepidum
-
gasotransmitter
-
sulfur-oxidizing
-
sulfide-oxidizing
- chlorobaculum
- 3-mercaptopyruvate
-
sulfane
-
limnetica
-
oscillatoria
-
urechis
-
echiuran
- unicinctus
-
anoxygenic
-
biogeochemistry
-
monotopic
- medicine
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The expected taxonomic range for this enzyme is: Archaea, Bacteria, Eukaryota
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EC NUMBER 
COMMENTARY 
1.8.5.4
-
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RECOMMENDED NAME
GeneOntology No.
bacterial sulfide:quinone reductase
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
n HS- + n quinone = polysulfide + n quinol
-
-
-
-
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oxidation
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
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SYSTEMATIC NAME
IUBMB Comments
sulfide:quinone oxidoreductase
Contains FAD. Ubiquinone, plastoquinone or menaquinone can act as acceptor in different species. This enzyme catalyses the formation of sulfur globules. It is also an important step in anoxygenic bacterial photosynthesis.
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
physiological function
metabolism
-
SQR is involved in elemental sulfur oxidation in sulfur-grown cells
metabolism
-
the enzyme plays a key role in the sulfide-dependent respiration and anaerobic photosynthesis
metabolism
-
SQR is involved in elemental sulfur oxidation in sulfur-grown cells
-
physiological function
-
SQR and the cytochrome bc complex are involved in sulfide-dependent respiration. Oxidation of sulfide by SQR is coupled, at least in part, to the proton-motive Q-cycle mechanism
physiological function
-
sulfide-quinone reductase is essential for photoautotrophic growth on sulfide and is involved in energy conversion, but not in detoxification
physiological function
-
sulfide-quinone reductase catalyzes anoxygenic photosynthesis in Oscillatoria limnetica
physiological function
-
SQR is involved in sulfide detoxification, in sulfide-dependent energy conservation processes and potenatially in the homeostasis of the neurotransmitter sulfide
physiological function
-
SQR is involved in sulfide detoxification, in sulfide-dependent energy conservation processes and potentially in the homeostasis of the neurotransmitter sulfide
physiological function
-
sulfide:quinone oxidoreductases are ubiquitous enzymes which have multiple roles: sulfide detoxification, energy generation by providing electrons to respiratory or photosynthetic electron transfer chains, and sulfide homeostasis
physiological function
-
human sulfide quinone oxidoreductase uses glutathione as an acceptor forming glutathione persulfide (GSSH), which is preferentially converted to thiosulfate by human rhodanese
physiological function
-
sulfide:quinone oxidoreductases are ubiquitous enzymes which have multiple roles: sulfide detoxification, energy generation by providing electrons to respiratory or photosynthetic electron transfer chains, and sulfide homeostasis
-
physiological function
-
sulfide-quinone reductase is essential for photoautotrophic growth on sulfide and is involved in energy conversion, but not in detoxification
-
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
sulfide + 2,3-dimethyl-1,4-naphthoquinone
sulfur + 2,3-dimethyl-1,4-naphthoquinol
-
-
-
-
?
sulfide + 2-methyl-3-methylthio-1,4-naphthoquinone
sulfur + 2-methyl-3-methylthio-1,4-naphthoquinol
-
lowest activity
-
-
?
sulfide + cysteine + coenzyme Q1
cysteine persulfide + reduced coenzyme Q1
-
-
-
-
?
sulfide + decylubiquinone + cyanide
sulfur + decylubiquinol + thiocyanate
-
-
-
-
?
sulfide + decylubiquinone + Escherichia coli thioredoxin
sulfur + decylubiquinol + ?
-
with Escherichia coli thioredoxin, SQR exhibits one-tenth of the cyanide-dependent activity
-
-
?
sulfide + decylubiquinone + sulfite
sulfur + decylubiquinol + ?
-
with sulfite, SQR exhibits one-tenth of the cyanide-dependent activity
-
-
?
sulfide + duroquinone 23
sulfur + duroquinol 23
-
% compared to the activity with decylubiquinone
-
-
?
sulfide + homocysteine + coenzyme Q1
homocysteine persulfide + reduced coenzyme Q1
-
-
-
-
?
sulfide + menadione
polysulfide + menadiol
-
25% compared to the activity with decylubiquinone
-
-
?
sulfide + plastoquinone-2
sulfur + plastoquinol-2
-
highest activity
-
-
?
sulfide + reduced glutathione + coenzyme Q1
glutathione persulfide + reduced coenzyme Q1
-
-
-
-
?
sulfide + sulfide + coenzyme Q
hydrogen disulfide + reduced coenzyme Q
-
-
-
-
?
sulfide + decylubiquinone
polysulfide + decylubiquinol
-
-
-
-
?
sulfide + decylubiquinone
polysulfide + decylubiquinol
-
-
-
-
?
sulfide + decylubiquinone
sulfur + decylubiquinol
-
-
-
?
sulfide + decylubiquinone
sulfur + decylubiquinol
-
-
-
-
?
sulfide + decylubiquinone
sulfur + decylubiquinol
-
-
-
-
?
sulfide + decylubiquinone
sulfur + decylubiquinol
-
-
-
?
sulfide + decylubiquinone
sulfur + decylubiquinol
-
-
-
-
?
sulfide + duroquinone
sulfur + duroquinol
-
23% compared to the activity with decylubiquinone
-
-
?
sulfide + duroquinone
sulfur + duroquinol
-
23% compared to the activity with decylubiquinone
-
-
?
sulfide + menadione
sulfur + menadiol
-
25% compared to the activity with decylubiquinone
-
-
?
sulfide + menadione
sulfur + menadiol
-
25% compared to the activity with decylubiquinone
-
-
?
sulfide + ubiquinone-1
sulfur + ubiquinol-1
-
15% compared to the activity with decylubiquinone
-
-
?
sulfide + ubiquinone-1
sulfur + ubiquinol-1
-
15% compared to the activity with decylubiquinone
-
-
?
additional information
?
-
the enzymatic reaction catalyzed by sulfide:quinone oxidoreductase includes the oxidation of sulfide compounds H2S, HS-, and S2- to soluble polysulfide chains or to elemental sulfur in the form of octasulfur rings
-
-
-
additional information
?
-
-
no activity with vitamin K1
-
-
-
additional information
?
-
cyanide, sulfite, or sulfide can act as the sulfane sulfur acceptor in reactions that exhibit pH optima at 8.5, 7.5, or 7.0, respectively, and produce thiocyanate, thiosulfate, or a putative sulfur analogue of hydrogen peroxide, i.e. H2S2, respectively. Sulfite is the physiological acceptor of the sulfur and the reaction is the predominant source of the thiosulfate produced during H2S oxidation by mammalian tissues
-
-
-
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
additional information
?
-
Q9Y6N5
cyanide, sulfite, or sulfide can act as the sulfane sulfur acceptor in reactions that exhibit pH optima at 8.5, 7.5, or 7.0, respectively, and produce thiocyanate, thiosulfate, or a putative sulfur analogue of hydrogen peroxide, i.e. H2S2, respectively. Sulfite is the physiological acceptor of the sulfur and the reaction is the predominant source of the thiosulfate produced during H2S oxidation by mammalian tissues
-
-
-
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
FAD
-
FAD is not covalently bound to the protein. Activity is not increased by the addition of FAD (0.020 mM) to the assay buffer; is not covalently bound to the protein, the cofactor is in an apolar environment, one equivalent of FAD per sulfide:quinone xidoreductase polypeptide
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
2n-nonyl-4-hydroxyquinoline-N-oxide
complete inhibition at 0.001 mM
2n-nonyl-4-hydroxyquinoline-N-oxide
-
complete inhibition at 0.001 mM
antimycin A
-
at 0.01 mM antimycin, residual sulfide:quinone oxidoreductase activity amounts to 53.4%
additional information
-
insentitive towards nonylhydroxyquinoline-N-oxide
-
additional information
-
not inhibited by 5n-undecyl-6-hydroxy-4,7-dioxobenzothiazole, 2-iodo-6-isopropyl-3-methyl-2'-4,4'-trinitrodiphenyl ether, and 3-(3',4'-dichlorophenyl)-1,1-dimelhylurea
-
additional information
-
insensitive to 3-(3'-4'-dichlorophenyl)-1,1-dimethylurea and 2-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenyl ether
-
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
sulfite
-
13.6fold increase in the rate of H2S oxidation in the presence of 0.6 mM sulfite
cyanide
-
SQR isolated from yeast mitochondria reduces decyl-ubiquinone after the addition of sulfide only in the presence of cyanide
cyanide
-
4.5fold increase in the rate of H2S oxidation in the presence of 1 mM cyanide
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.014
ubiquinone-2
-
apparent value, at pH 7.0, temperature not specified in the publication
0.0016
ubiquinone-4
-
in 50 mM Tris-HCl, pH 7.4, 40°C; pH 7.4, temperature not specified in the publication
0.00643
ubiquinone-9
-
in 50 mM Tris-HCl, pH 7.4, 40°C; pH 7.4, temperature not specified in the publication
0.002
decylubiquinone
-
in 10 mM bis-Tris-HCl, pH 6.5, temperature not specified in the publication
0.00216
decylubiquinone
-
in 50 mM Tris-HCl, pH 7.4, 40°C; pH 7.4, temperature not specified in the publication
0.003
decylubiquinone
-
mutant enzyme H196A, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication; wild type enzyme, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.0031
decylubiquinone
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
0.00343
decylubiquinone
-
wild type enzyme, at pH 7.0 and 23°C
0.00425
decylubiquinone
-
mutant enzyme C128A, at pH 7.0 and 23°C
0.0054
decylubiquinone
-
mutant enzyme H132A, at pH 7.0 and 23°C
0.00585
decylubiquinone
-
mutant enzyme C128S, at pH 7.0 and 23°C
0.022
decylubiquinone
-
in 50 mM 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol (pH 6.5), temperature not specified in the publication
0.027
decylubiquinone
-
mutant enzyme H131A, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.028
decylubiquinone
-
Km above 0.028 mM, mutant enzyme V300D, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.03
decylubiquinone
-
pH 7.5, 60°C, membrane-bound wild-type enzyme; pH 7.5, 60°C, wild-type enzyme
0.032
decylubiquinone
-
pH 7.5, 60°C, membrane-bound mutant enzyme M380N
0.033
decylubiquinone
-
pH 7.5, 60°C, membrane-bound mutant enzyme Y383Q/F384K
0.036
decylubiquinone
-
pH 7.5, 60°C, cytoplasmic mutant enzyme Y383Q/F384K
0.031
plastoquinone-1
-
in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
0.04
plastoquinone-1
in 10 mM potassium HEPES (pH 7.4), 10 mM MgCl2, 10 mM KCl, temperature not specified in the publication
0.04
plastoquinone-1
-
in 10 mM potassium HEPES (pH 7.4), 10 mM MgCl2, 10 mM KCl, temperature not specified in the publication
0.002
Sulfide
-
in 10 mM bis-Tris-HCl, pH 6.5, temperature not specified in the publication
0.0028
Sulfide
-
in 50 mM 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol (pH 6.5), temperature not specified in the publication
0.005
Sulfide
-
wild type enzyme, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.00594
Sulfide
-
in 50 mM Tris-HCl, pH 7.4, 40°C; pH 7.4, temperature not specified in the publication
0.008
Sulfide
-
in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
0.0109
Sulfide
-
with coenzyme Q and cyanide as cosubstrates, at pH 8.0 and 25°C
0.011
Sulfide
-
mutant enzyme H131A, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.015
Sulfide
-
mutant enzyme H196A, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.02
Sulfide
in 10 mM potassium HEPES (pH 7.4), 10 mM MgCl2, 10 mM KCl, temperature not specified in the publication
0.02
Sulfide
-
in 10 mM potassium HEPES (pH 7.4), 10 mM MgCl2, 10 mM KCl, temperature not specified in the publication
0.026
Sulfide
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
0.042
Sulfide
-
apparent value, at pH 7.0, temperature not specified in the publication
0.046
Sulfide
-
pH 7.5, 60°C, membrane-bound mutant enzyme Y383Q/F384K
0.077
Sulfide
-
pH 7.5, 60°C, cytoplasmic mutant enzyme Y383Q/F384K; pH 7.5, 60°C, membrane-bound wild-type enzyme; pH 7.5, 60°C, wild-type enzyme
0.4
Sulfide
-
Km above 0.4 mM, mutant enzyme V300D, in 250 mM Tris-HCl (pH 8.0), temperature not specified in the publication
0.0054
ubiquinone-1
-
in 50 mM Tris-HCl, pH 7.4, 40°C; pH 7.4, temperature not specified in the publication
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.6
decylubiquinone
-
pH 7.5, 60°C, membrane-bound wild-type enzyme
0.62
decylubiquinone
-
pH 7.5, 60°C, membrane-bound mutant enzyme M380N
0.82
decylubiquinone
-
pH 7.5, 60°C, membrane-bound mutant enzyme Y383Q/F384K
1.2
decylubiquinone
-
pH 7.5, 60°C, cytoplasmic mutant enzyme Y383Q/F384K
0.1
Sulfide
-
mutant enzyme C160A, at pH 7.0 and 23°C; mutant enzyme C356S, at pH 7.0 and 23°C
0.82
Sulfide
-
pH 7.5, 60°C, membrane-bound mutant enzyme Y383Q/F384K
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.05
2-n-heptyl-4-hydroxy-quinone-N-oxide
Acidithiobacillus ferrooxidans
-
at pH 7.0, temperature not specified in the publication
0.00014
n-nonyl-4-hydroxyquinoline-N-oxide
Pseudanabaena limnetica
-
in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
0.0005
2-heptylquinolin-4-ol 1-oxide
Allochromatium vinosum
-
in 50 mM Tris-HCl (pH 7.5), temperature not specified in the publication
0.00076
2-n-nonyl-4-hydroxyquinoline-N-oxide
Chlorobaculum thiosulfatiphilum
-
in 20 mM Tris-HCl, pH 7.8, at 24°C
0.006
2-n-nonyl-4-hydroxyquinoline-N-oxide
Aquifex aeolicus
-
in 50 mM Bis-Tris (pH 7.0), at 20°C
0.015
antimycin A
Paracoccus denitrificans
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
0.22
antimycin A
Acidithiobacillus ferrooxidans
-
at pH 7.0, temperature not specified in the publication
0.000049
aurachin C
Pseudanabaena limnetica
-
in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
0.028
aurachin C
Paracoccus denitrificans
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
0.5
cyanide
Allochromatium vinosum
-
in 50 mM Tris-HCl (pH 7.5), temperature not specified in the publication
0.54
cyanide
Acidithiobacillus ferrooxidans
-
at pH 7.0, temperature not specified in the publication
0.004
Myxothiazol
Allochromatium vinosum
-
in 50 mM Tris-HCl (pH 7.5), temperature not specified in the publication
0.022
Myxothiazol
Paracoccus denitrificans
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
0.039
Myxothiazol
Acidithiobacillus ferrooxidans
-
at pH 7.0, temperature not specified in the publication
0.02
Stigmatellin
Paracoccus denitrificans
-
in 50 mM Bis-Tris (pH 6.5), temperature not specified in the publication
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
0.018
-
enzyme from washed membrane, in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
0.1
-
crude extract, in 10 mM bis-Tris-HCl, pH 6.5, temperature not specified in the publication
0.11
-
cell-free extract, at pH 7.0, temperature not specified in the publication
0.127
-
using 2,3-dimethyl-1,4-naphthoquinone as cosubstrate, at 50°C, pH 6.5
1.88
-
after 105fold purification, in 10 mM HEPES, pH 7.4, 10 mM MgCl, 10 mM KCl, at 22°C
3.5
20.55
-
after 186.8fold purification, at pH 7.0, temperature not specified in the publication
55.4
-
in 50 mM Tris-HCl (pH 7.5), temperature not specified in the publication
3.5
-
after 35fold purification, in 10 mM bis-Tris-HCl, pH 6.5, temperature not specified in the publication
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.5
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
20 - 70
-
with 0.015 mM decylubqiuinone reduced/mg protein/min, the activity at 70°C is 5fold higher than the activity at 20°C
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
-
enzyme mRNA expression during sulfide exposure in the body wall and hindgut increases in a time- and concentration-dependent manner that increases significantly at 12 h and continuously increases with time. At the protein level, enzyme expression in the two tissues increases significantly at 12 h after application of 50 microM sulfide and 6 h after 150 microM, and then continues to increase
-
enzyme mRNA expression during sulfide exposure in the body wall and hindgut increases in a time- and concentration-dependent manner that increases significantly at 12 h and continuously increases with time. At the protein level, enzyme expression in the two tissues increases significantly at 12 h after application of 50 microM sulfide and 6 h after 150 microM, and then continues to increase
-
in the brain, H2S signal termination occurs partially through protein sequestration and partially through catabolism not involving sulfide:quinone reductase
the number of Sqrdl transcripts in the brain increases with increasing age
-
termination of endogenous H2S signalling in the colonic muscularis externa occurs via catabolism to thiosulfate and sulfate partially via a mechanism involving sulfide:quinone reductase
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
periplasmic surface of the cytoplasmic membrane
-
-
periplasmic surface of the cytoplasmic membrane
-
-
-
the C-terminal amphiphilic helix is important for membrane binding
-
the C-terminal amphiphilic helix is important for membrane binding
-
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PDB
SCOP
CATH
ORGANISM
UNIPROT
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
Acidithiobacillus ferrooxidans (strain ATCC 23270 / DSM 14882 / CIP 104768 / NCIMB 8455)
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
47000
48000
57000
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
dimer
homodimer
homotrimer
monomer
?
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x * 47000, SDS-PAGE; x * 47290, deduced from amino acid sequence
?
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x * 47000, SDS-PAGE; x * 47290, deduced from amino acid sequence
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
hanging drop vapor diffusion method, using 2.2 M NH4H2PO4 and 100 mM Tris-HCl, pH 8.5 (final pH of the solution is 4.5), or 2.2 M NH4H2PO4/K2HPO4 at pH 4.5
-
crystal structures of the wild-type enzyme in complex with sodium selenide and gold(I) cyanide. Mechanism for the reduction of sulfides to elemental sulfur may involve nucleophilic attack of Cys356 on C4A atom of FAD or alternatively, an alternative anionic radical mechanism by direct electron transfer from Cys356 to the isoalloxazine ring of FAD
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hanging drop vapor diffusion method, using 30% (w/v) PEG 600, 0.1 M bis-Tris pH 5.5, 0.1 M ammonium sulfate
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native or in complex with decylubiquinone, hanging drop vapor diffusion method, using 30% (w/v) polyethylene glycol 600, 0.1 M 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol (pH 5.5 or pH 6.5), 0.1 M magnesium sulfate, and 0.05% (w/v) n-dodecyl beta-D-maltoside
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; crystallization in two crystal forms of hexagonal, prism shape and thin, elongated shape
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hanging drop vapor diffusion method, using 2.0 M ammonium sulfate and 4% (v/v) PEG 400
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
0 - 45
-
the recombinant enzyme is highly stable when incubated at 0°C, 4°C, 23°C or 30°C with more than 90% of the activity remaining after 7 h. It is less stable at 37°C and loses about 40% of the activity in the first 7.5 h. The activity of the enzyme decreases more rapidly at 45°C with a half-life of approximately 5 h
95
-
the reaction with membranes that have been heated for more than 2 h at 95°C is negligible
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
4C, protein is stable and monodisperse in 50 mM dodecyl-D-maltoside for weeks, either in the absence of salt or in the presence of N 1 M NaCl
-
4°C, purified protein in 3% (w/v) dodecyl-beta-D-maltoside either in the absence of salt or in the presence of N 1 M NaCl, six weeks, no loss of activity
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80°C, purified protein in 3% (w/v) dodecyl-beta-D-maltoside either in the absence of salt or in the presence of N 1 M NaCl, one day, 50% loss of activity
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
ammonium sulfate precipitation, Hi-Trap column chromatography, and Superdex 200 gel filtration
-
ammonium sulfate precipitation, phenyl-Toyopearl column chromatography, and TSKgel G3000 gel filtration
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ammonium sulfate precipitation, phenyl-TSK column chromatography, T SK-gel filtration and analytical gel filtration
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DEAE-cellulose column chromatography and Mono Q column chromatography
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MonoQ column chromatography, TSK-1 gel filtration, and TSK-2 gel filtration
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Ni-NTA column chromatography
nickel affinity column chromatography, and Superdex 200 gel filtration
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli BL21(DE3) cells
expressed in Escherichia coli BL21(DE3) or Rosetta-gami(DE3) cells as a thioredoxin-fusion protein in inclusion bodies in an inactive form
-
expressed in the Rhodobacter capsulatus SB1003 sqr deletion mutant
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expression at low temperature in Escherichia coli by using an optimized synthetic gene and cold-adapted chaperonins
-
expression in Escherichia coli
expressed in Escherichia coli BL21(DE3) cells
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
enzyme mRNA expression during sulfide exposure in the body wall and hindgut increases in a time- and concentration-dependent manner that increases significantly at 12 h and continuously increases with time
-
SQR activity is induced for 2 h in the presence of 1.25 mM sulfide and light
the number of Sqrdl transcripts in the brain increases with increasing age
SQR activity is induced for 2 h in the presence of 1.25 mM sulfide and light
SQR activity is induced for 2 h in the presence of 1.25 mM sulfide and light
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C128A
C128S
C160A
C160S
-
the mutant shows strongly reduced activity compared to the wild type enzyme
C356S
H132A
H198A
S126A
-
about 35% of wild-type activity in assay with decylubiquinone
C128A
-
about 35% of wild-type activity in assay with decylubiquinone
-
C160A
-
loss of activity in assay with decylubiquinone, about 35% of wild-type activity for reduction of FAD fluorescence by Na2S
-
H132A
-
about 40% of wild-type activity in assay with decylubiquinone
-
H198A
-
about 60% of wild-type activity in assay with decylubiquinone
-
S126A
-
about 35% of wild-type activity in assay with decylubiquinone
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L379D
-
all of the expressed protein is membrane-bound, the mutant enzyme is inactive; inactive mutant enzyme, all of the expressed protein is membrane-bound
L379D/M380N
-
both the membrane-bound and soluble forms of this protein are inactive; the mutant protein is found in both the cytoplasmic and membrane fractions in equal proportions after disruption of the Escherichia coli cells, and each fraction has the same FAD content as the membrane bound wild type enzyme (about 50%)
L379N
-
all of the expressed protein is membrane-bound, the mutant enzyme is inactive; the mutant enzyme is inactive due to a perturbation of the decylubiquinone binding site
M380N
-
mutation results in protein that is entirely membrane-bound, but which has the same activity as wild type enzyme; this is one of the two mutations in the L379D/M380N double mutant. The M380N mutation by itself results in protein that is entirely membrane-bound, but which has the same activity as wild type enzyme
Y383Q/F384K
-
both the soluble and membrane-bound versions of this double-mutant are catalytically active. The membrane-bound mutant enzyme has a specific activity about 30% higher than the wild type enzyme and the Km for sulfide is about half of the value found for the wild type enzyme. The water-soluble version of this mutant enzyme is twice as active as the wild type enzyme and the Km values for both sulfide and decylubiquinone are about the same as the wild type, membrane-bound form; this mutant protein is expressed in a yield similar to the wild type enzyme and is found equally in the cytoplasmic and membrane fractions after cell disruption. The isolated proteins from each fraction contain FAD to the same extent as the wild type enzyme. Both the soluble and membrane bound versions of this double-mutant are catalytically active. The membrane-bound mutant enzyme has a specific activity about 30% higher than the wild type enzyme and the Km for sulfide is about half of the value found for the wild type (0.046 mM vs.0.077 mM). The water-soluble version of this mutant enzyme is twice as active as the wild type SQR (1.20 vs. 0.60 nmol quinone reduced/s* nM FAD) and the Km values for both sulfide and decylubiquinone are about the same as the wild type, membrane-bound form
Y383Q/F384K/L379D/M380N
-
the mutant protein is found entirely in the cytoplasmic fraction but there is no catalytic activity
L379D/M380N
-
both the membrane-bound and soluble forms of this protein are inactive
-
Y383Q/F384K
-
both the soluble and membrane-bound versions of this double-mutant are catalytically active. The membrane-bound mutant enzyme has a specific activity about 30% higher than the wild type enzyme and the Km for sulfide is about half of the value found for the wild type enzyme. The water-soluble version of this mutant enzyme is twice as active as the wild type enzyme and the Km values for both sulfide and decylubiquinone are about the same as the wild type, membrane-bound form; this mutant protein is expressed in a yield similar to the wild type enzyme and is found equally in the cytoplasmic and membrane fractions after cell disruption. The isolated proteins from each fraction contain FAD to the same extent as the wild type enzyme. Both the soluble and membrane bound versions of this double-mutant are catalytically active. The membrane-bound mutant enzyme has a specific activity about 30% higher than the wild type enzyme and the Km for sulfide is about half of the value found for the wild type (0.046 mM vs.0.077 mM). The water-soluble version of this mutant enzyme is twice as active as the wild type SQR (1.20 vs. 0.60 nmol quinone reduced/s* nM FAD) and the Km values for both sulfide and decylubiquinone are about the same as the wild type, membrane-bound form
-
Y383Q/F384K/L379D/M380N
-
the mutant protein is found entirely in the cytoplasmic fraction but there is no catalytic activity
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C94S
H131A
-
20% activity at pH 6.5 and 27% activity at (optimum) pH 4.5 compared to the wild type enzyme
H196A
-
38% activity at pH 6.5 and 40% activity at (optimum) pH 6.2 compared to the wild type enzyme
additional information
C128A
-
in the decylubiquinone assay, the mutant shows 30-35% activity compared to the wild type enzyme. However, in the FAD reduction assay, both the wild type and the Cys128Ala variant are fully active (100%)
C128A
-
about 35% of wild-type activity in assay with decylubiquinone
C128A
-
the mutant shows strongly reduced activity compared to the wild type enzyme
C128S
-
the mutant shows strongly reduced activity compared to the wild type enzyme
C160A
-
loss of activity in assay with decylubiquinone, about 35% of wild-type activity for reduction of FAD fluorescence by Na2S
C160A
-
the mutant shows severely reduced activity compared to the wild type enzyme
C356S
-
loss of activity in assay with decylubiquinone, loss of activity for reduction of FAD fluorescence by Na2S
C356S
-
the mutant shows severely reduced activity compared to the wild type enzyme
H132A
-
about 40% of wild-type activity in assay with decylubiquinone
H132A
-
the mutant shows strongly reduced activity compared to the wild type enzyme
H198A
-
about 60% of wild-type activity in assay with decylubiquinone
H198A
-
the mutant shows severely reduced activity compared to the wild type enzyme
additional information
-
in the truncation mutant SQRT1 a stop codon is introduced to eliminate the last 21 amino acids from the C-terminus, removing one putative amphiphilic helix. In construct SQRT2, the last 45 amino acids are removed, thus eliminating both of the amphiphilic helices. Both SQRT1 and SQRT2 when expressed in Escherichia coli result in water-soluble proteins. In each case the yield of protein is nearly 5-fold higher than the wild type construct, in which the recombinant protein is bound to the membrane. The FAD content of each of the truncated proteins, as well as the characteristics of the absorption spectra, is identical to those of the detergent-solubilized, wild type enzyme. No sulfide:decylubiquinone oxidoreductase activity is observed in either case
additional information
-
in the truncation mutant SQRT1 a stop codon is introduced to eliminate the last 21 amino acids from the C-terminus, removing one putative amphiphilic helix. In construct SQRT2, the last 45 amino acids are removed, thus eliminating both of the amphiphilic helices. Both SQRT1 and SQRT2 when expressed in Escherichia coli result in water-soluble proteins. In each case the yield of protein is nearly 5-fold higher than the wild type construct, in which the recombinant protein is bound to the membrane. The FAD content of each of the truncated proteins, as well as the characteristics of the absorption spectra, is identical to those of the detergent-solubilized, wild type enzyme. No sulfide:decylubiquinone oxidoreductase activity is observed in either case
-
additional information
-
no SQR activity is found in membranes from mutants F14 and 22/11. Membranes of strain F14sn show 6-7times the activity of the membranes from the wild type strain
additional information
-
no SQR activity is found in membranes from mutants F14 and 22/11. Membranes of strain F14sn show 6-7times the activity of the membranes from the wild type strain
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
medicine
-
termination of endogenous H2S signalling in the colonic muscularis externa occurs via catabolism to thiosulfate and sulfate partially via a mechanism involving sulfide:quinone reductase. In the brain, H2S signal termination occurs partially through protein sequestration and partially through catabolism not involving sulfide:quinone reductase
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LINKS TO OTHER DATABASES (specific for EC-Number 1.8.5.4)
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