1.8.5.4: bacterial sulfide:quinone reductase
This is an abbreviated version!
For detailed information about bacterial sulfide:quinone reductase, go to the full flat file.
Word Map on EC 1.8.5.4
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1.8.5.4
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sulfur
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h2s
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thiosulfate
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persulfide
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polysulfide
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acidithiobacillus
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sulfurtransferase
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sulfide-oxidizing
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rhodanese
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sulfane
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ferrooxidans
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3-mercaptopyruvate
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anoxygenic
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sulfur-oxidizing
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chemolithotrophic
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sulfide-dependent
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echiuran
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unicinctus
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limnetica
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urechis
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monotopic
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oscillatoria
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tepidum
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chlorobaculum
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sulfide-rich
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medicine
- 1.8.5.4
- sulfur
- h2s
- thiosulfate
- persulfide
- polysulfide
- acidithiobacillus
- sulfurtransferase
-
sulfide-oxidizing
- rhodanese
-
sulfane
- ferrooxidans
- 3-mercaptopyruvate
-
anoxygenic
-
sulfur-oxidizing
-
chemolithotrophic
-
sulfide-dependent
-
echiuran
- unicinctus
- limnetica
-
urechis
-
monotopic
- oscillatoria
- tepidum
- chlorobaculum
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sulfide-rich
- medicine
Reaction
n HS-
+
n quinone
=
Synonyms
CmSQR, CpSQR, CT1087, HMT2, III SQR, membrane-bound sulfide:quinone oxidoreductases, SQOR, SQR, Sqrdl, sqrF, Suden_1879, Suden_2082, Suden_619, sulfide quinone oxidoreductase, sulfide quinone reductase, sulfide-quinone oxidoreductase, sulfide-quinone reductase, sulfide: quinone oxidoreductase, sulfide:decylubiquinone oxidoreductase, sulfide:quinone oxidoreductase, sulfidequinone reductase-like protein, TrSqrF, type I SQR, type III sulfide:quinone oxidoreductase, type VI sulfide:quinone oxidoreductase
ECTree
1.8.5.4 bacterial sulfide:quinone reductaseAdvanced search results
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results (Engineering
Engineering on EC 1.8.5.4 - bacterial sulfide:quinone reductase
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PROTEIN VARIANTS 
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
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about 35% of wild-type activity in assay with decylubiquinone
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C160A
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loss of activity in assay with decylubiquinone, about 35% of wild-type activity for reduction of FAD fluorescence by Na2S
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H132A
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about 40% of wild-type activity in assay with decylubiquinone
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H198A
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about 60% of wild-type activity in assay with decylubiquinone
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S126A
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about 35% of wild-type activity in assay with decylubiquinone
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L379D
L379D/M380N
L379N
M380N
Y383Q/F384K
Y383Q/F384K/L379D/M380N
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the mutant protein is found entirely in the cytoplasmic fraction but there is no catalytic activity
L379D/M380N
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both the membrane-bound and soluble forms of this protein are inactive
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Y383Q/F384K
Y383Q/F384K/L379D/M380N
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the mutant protein is found entirely in the cytoplasmic fraction but there is no catalytic activity
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H131A
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20% activity at pH 6.5 and 27% activity at (optimum) pH 4.5 compared to the wild type enzyme
H196A
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38% activity at pH 6.5 and 40% activity at (optimum) pH 6.2 compared to the wild type enzyme
C121A
site-directed mutagenesis of gene sqrF, inactive mutant
C272A
site-directed mutagenesis of gene sqrF, the mutant is more sensitive to iodoacetamide inhibition compared to wild-type. The kcat of the C272A variant slightly decreases, and the affinity of the C272A mutant for duroquinone is lower (increased Km) than those of the wild-type TrSqrF enzyme, but the mutated enzyme has a similar affinity for the sulfide substrate
C332A
site-directed mutagenesis of gene sqrF, the mutant is much more sensitive to iodoacetamide inhibition compared to wild-type. The kcat and the Vmax values for the C332A variant catalyzed reaction are each one order of magnitude smaller than those data obtained with the wild-type enzyme which coincides with the significantly diminished specific activity measured for this mutant enzyme
C49A
site-directed mutagenesis of gene sqrF, the C49A enzyme has slightly increased Vmax and kcat values as compared to those of wild-type TrSqrF, but decreased affinity for the sulfide substrate
additional information
C128A
the mutant shows strongly reduced activity compared to the wild type enzyme
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
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
the mutant shows strongly reduced activity compared to the wild type enzyme
H132A
about 40% of wild-type activity in assay with decylubiquinone
H198A
about 60% of wild-type activity in assay with decylubiquinone
H198A
the mutant shows severely reduced activity compared to the wild type enzyme
L379D
-
all of the expressed protein is membrane-bound, the mutant enzyme is inactive
L379D
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inactive mutant enzyme, all of the expressed protein is membrane-bound
L379D/M380N
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both the membrane-bound and soluble forms of this protein are inactive
L379D/M380N
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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
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all of the expressed protein is membrane-bound, the mutant enzyme is inactive
L379N
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the mutant enzyme is inactive due to a perturbation of the decylubiquinone binding site
M380N
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mutation results in protein that is entirely membrane-bound, but which has the same activity as wild type enzyme
M380N
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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
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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
Y383Q/F384K
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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
-
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
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Y383Q/F384K
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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
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additional information
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sulfide present in the up-flow anaerobic sludge blanket (UASB)-treated post tanning wastewater is oxidized into elemental sulfur using sulfide:quinone oxidoreductase (SQR) immobilized on functionalized carbon-silica matrix (FCSM) in a packed bed reactor. Optimum conditions for immobilization of SQR onto FCSM are pH, 7.0, 40°C, and 10mg/g SQR during 240 min. The immobilization of SQR onto FCSM obeys the Langmuir isotherm model. The maximum sulfide oxidation is 99% at HRT of 15 h with residual sulfide of 2.4 mg/l. The formation of elemental Sulphur is confirmed by XRD studies. Enzyme immobilization method evaluation and optimization, adsorption kinetics and thermodynamics, detailed overview
additional information
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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
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construction of soluble mutant variants, unable to bind to the membrane, lacking either four hydrophobic residues from the last C-terminal helix (quadruple-mutant or YL), the complete last C-terminal helix (truncated 1 or T1) or the last two C-terminal helices (truncated 2 or T2). Localization study of tagged wild-type and mutant enzymes and enzyme fragments in Escherichia coli cells, overview
additional information
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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
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additional information
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construction of soluble mutant variants, unable to bind to the membrane, lacking either four hydrophobic residues from the last C-terminal helix (quadruple-mutant or YL), the complete last C-terminal helix (truncated 1 or T1) or the last two C-terminal helices (truncated 2 or T2). Localization study of tagged wild-type and mutant enzymes and enzyme fragments in Escherichia coli cells, overview
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additional information
for analysis of the membrane association of CpSQR: construction of C-terminally truncated CpSQR mutants containing the N-terminal fragment sx, where x stands for the number of amino acid residues from the N terminus (x = 26, 49, 71, 83, 107, 115, 128, 157, 176, 230, 359, or 450). Generation of a CpSQR-PhoA fusion protein and comparison with the TolB-PhoA fusion protein. Cells with the fusion of CpSQR and PhoA show SQR activity, while other fusions with SQR fragments have no SQR activity, full-length PhoA and TolB-PhoA are used as the positive controls
additional information
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preparation and analysis of sulfide:quinone oxidoreductase immobilized carbon matrix for the treatment of sulfide rich post-tanning wastewater. Enzyme production is optimized using respone surface methodology. Optimized conditions for enzyme immobilization from cell-free enzyme exract on carbon silica matrix (CSM) are pH 7.0, 40°C, and enzyme protein concentration of 7 mg/g over 300 min, while on functionalized carbon silica matrix (FCSM) they are pH 7.0, 40°C, and enzyme protein concentration of 10 mg/g over 240 min. The CSM-SQR packed bed reactors remove 99% with residual 3 mg/l sulfide at optimum hydraulic retention time (HRT) of 15 h, the FCSM-SQR packed bed reactors remove 99% with residual 2.5 mg/l sulfide at optimum hydraulic retention time (HRT) of 9 h. Method development and evaluation, overview
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
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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
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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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additional information
construction and analysis of an enzyme knockout strain DELTAsqr, phenotypes, overview
additional information
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construction and analysis of an enzyme knockout strain DELTAsqr, phenotypes, overview
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additional information
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construction and analysis of an enzyme knockout strain DELTAsqr, phenotypes, overview
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additional information
recombinant Escherichia coli expressing SQR and PDO from strain PCC7002 oxidizes sulfide to sulfite and thiosulfate
additional information
construction of enzyme mutants with reduced activity compared to wild-type
additional information
construction of a Thiocapsa roseopersicina fcc, sqrD, and sqrF deletion mutant strain FOQRON from wild-type strain FOQR. Results with the C332A mutant TrSqrF variant are immediately more evident than the C49 and C272 mutations
additional information
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construction of a Thiocapsa roseopersicina fcc, sqrD, and sqrF deletion mutant strain FOQRON from wild-type strain FOQR. Results with the C332A mutant TrSqrF variant are immediately more evident than the C49 and C272 mutations
