1.8.3.1: sulfite oxidase
This is an abbreviated version!
For detailed information about sulfite oxidase, go to the full flat file.
Word Map on EC 1.8.3.1
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1.8.3.1
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molybdenum
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sulfur
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xanthine
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heme
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thiosulfate
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moco
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epr
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seizures
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molybdopterin
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molybdoenzymes
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sulfur-containing
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tungsten
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molybdenum-containing
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pterin
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s-sulfocysteine
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soxs
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sulfurtransferase
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ectopia
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low-ph
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pyranopterins
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lentis
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dithiolene
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amidoxime
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eseem
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hyperfine
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food industry
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agriculture
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high-ph
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analysis
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oxidase-deficient
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medicine
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xanthinuria
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marc
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molecular biology
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encephalomalacia
- 1.8.3.1
- molybdenum
- sulfur
- xanthine
- heme
- thiosulfate
- moco
- epr
- seizures
- molybdopterin
-
molybdoenzymes
-
sulfur-containing
- tungsten
-
molybdenum-containing
- pterin
- s-sulfocysteine
- soxs
- sulfurtransferase
-
ectopia
-
low-ph
-
pyranopterins
- lentis
-
dithiolene
-
amidoxime
-
eseem
-
hyperfine
- food industry
- agriculture
-
high-ph
- analysis
-
oxidase-deficient
- medicine
-
xanthinuria
-
marc
- molecular biology
- encephalomalacia
Reaction
Synonyms
At-SO, AtSOX, CG7280, HSO, NIA, oxidase, sulfite, PSO, Shopper, SO, SorT, SOX, sulfite oxidase, sulfite oxidase homologue, sulfite: acceptor oxidoreductase, sulfite:acceptor oxidoreductase, sulfite:oxygen oxidoreductase, sulphite oxidase cytochrome b9, SUOX, YedY, YedYZ, ZmSO
ECTree
1.8.3.1 sulfite oxidaseAdvanced search results
results (
results (Engineering
Engineering on EC 1.8.3.1 - sulfite oxidase
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PROTEIN VARIANTS 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
R138Q
the side chain nitrogen of the Gln appears to be within the coordination sphere of the Mo
Y322F/R450M
introduction of predicted catalytic site residues of assimilatory nitrate reductase, markedly decreased ability to bind sulfite at pH 8.5
A208D
C242S/C253S/C260S/C451S
site-directed mutagenesis, mutation of the four active site Cys residues
D342K
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significant decrease in the intramolecular electron transfer rate constant, kcat value is higher than the corresponding intramolecular electron transfer rate constant values, and the redox potentials of both metal centers are affected
F57A
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the size and hydrophobicity of F57 play an important role in modulating the heme potential, residue F57 also affects the intramolecular electron transfer rate
F57Y
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the size and hydrophobicity of F57 play an important role in modulating the heme potential, residue F57 also affects the intramolecular electron transfer rate
F79A
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the size and hydrophobicity of F57 play an important role in modulating the heme potential, residue F57 also affects the intramolecular electron transfer rate
G473A
G473D
G473W
H304A R309H
site-directed mutagenesis, a mutation that removes the charge, hydrogen bonding, and is of smaller size, shows a decrease in Ksulfite m , thus binding sulfite more efficiently than the wild-type, kcat is increased compared to wild-type
H304R/R309H
site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme
H61Y/R160G
the mutations are associated with isolated sulfite oxidase deficiency
H90F
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interactions of H90 with a heme propionate group destabilize the Fe(III) state of the heme
H90Y
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interactions of H90 with a heme propionate group destabilize the Fe(III) state of the heme
K322R
site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme
R160K
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the intramolecular electron transfer rate constant for the mutant enzyme is about one-fourth that of the wild-type enzyme
R160Q
R212A/G473D
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mutant is able to oligomerize but has undetectable activity, significant random-coil formation
R309E
site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme, mutant R309E, which shows the greatest increase in activity, also shows the greatest increase in Km
R309H
site-directed mutagenesis, the mutant shows altered kinetics and reaction rates compared to the wild-type enzyme, purified R309H mutant enzyme has substantially increased catalytic activity and a slightly less efficient Km sulfite compared to the wild-type enzyme
R472D
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significant decrease in the intramolecular electron transfer rate constant, and the redox potentials of both metal centers are affected
R472D/D342K
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mutation reverses the charges of the salt bridge components, large decrease in intramolecular electron transfer rate constant
R472M
R472Q
Y343F
Y343X
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isolated sulfite oxidase deficiency, shows early neonatal leukoencephalopathy and extensive symmetric cerebral injury especially white matter and basal ganglia
Y83A
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mutation is located on the surface of the heme domain, but not in direct contact with the heme or the propionate groups, little effect on either intramolecular electron transfer or the heme potential
Y83F
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mutation is located on the surface of the heme domain, but not in direct contact with the heme or the propionate groups, little effect on either intramolecular electron transfer or the heme potential
additional information
A208D
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the intramolecular electron transfer rate constants at pH 6.0 are decreased by 3 orders of magnitude relative to that of the wild type, the active site structure of the Mo(V) form of A208D is different from that of the wild type
G473A
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mutant is able to dimerize and has steady-state activity comparable to that of the wild type, stopped-flow analysis of the reductive half-reaction of this variant yields a rate constant nearly 3 times higher than that of the wild type
G473D
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monomer, mutant is severely impaired both in the ability to bind sulfite and in catalysis, with a second-order rate constant 5 orders of magnitude lower than that of the wild type, significant random-coil formation
G473D
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monomer, the Mo(V) active site structure is similar to that of the wild type, and the IET rate constant is only 2.6fold smaller than that of the wild type
G473W
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monomer, mutant with 5fold higher activity than G473D and nearly wild-type activity at pH 7.0 when ferricyanide is the electron acceptor, significant random-coil formation
R160Q
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the intramolecular electron transfer rate constant for the mutant enzyme at pH 6.0 is decreased by nearly 3 orders of magnitude relative to wild-type enzyme. The intramolecular electron transfer is rate-limiting in the catalytic cycle of the mutant, fatal impact of this mutation in patients with this genetic disorder
R160Q
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at least three different Mo(V) species of R160Q exist as a function of pH (low pH type 1 and type 2, and high-pH). Mo(V) species with a blocked form of sulfite oxidase, with sulfate coordinated to the Mo center is the only species at pH higher or equal as 6 and remains a significant form at physiological pH, is six-coordinate and has a nearby exchangeable proton that is likely to be hydrogen-bonded to an oxygen of the sulfate ligand. The blocked structure of R160Q represents a catalytic dead end that contributes to the lethality of this mutant under physiological conditions
R160Q
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clinical mutant, has a six-coordinate pseudooctahedral active site with coordination of glutamine Oepsilon to molybdenum
R160Q
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mutation increases the Km for sulfite and decreases the kcat, resulting in a 1000fold decrease in catalytic efficiency. Reveals an increase in coordination number for the Mo, from 5 to 6
R472M
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introduction of predicted catalytic site residues of assimilatory nitrate reductase, kinetic analysis
R472M
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significant decrease in the intramolecular electron transfer rate constant, kcat value is higher than the corresponding intramolecular electron transfer rate constant values, and the redox potentials of both metal centers are affected
R472Q
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introduction of predicted catalytic site residues of assimilatory nitrate reductase, kinetic analysis
R472Q
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significant decrease in the intramolecular electron transfer rate constant, kcat value is higher than the corresponding intramolecular electron transfer rate constant values, and the redox potentials of both metal centers are affected
Y343F
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in the mutant enzyme using cytochrome c as electron acceptor, turnover number is somewhat impaired, 34% of the wild-type activity at pH 8.5. The KM-value for the mutant enzyme shows a 5fold increase over wild-type. Reduction of the molybdenum center of the Y343 F variant by sulfite is more significantly impaired at high pH than at low pH
Y343F
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increase in the Km-value for sulfite and a decrease in turnover number results in a 23fold attenuation in the specificity constant turnover (ratio of number to KM-value for sulfite) at optimum pH value of 8.25
Y343F
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under low pH conditions the active site of Y343F is in the blocked form, with the Mo(V) center coordinated by sulfate. The Y343F mutation increases the apparent pKa of the transition from the low pH to high pH forms by ca. 2 pH units. An additional low pH form that has no exchangeable protons
additional information
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a 1 bp insertion located in exon 4 of the bovine SUOX gene (c.363-364insG) is the causative mutation for arachnomelia
additional information
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optimized expression in Escherichia coli, untagged and His-tagged enzyme, expression in presence of tungstate
additional information
isolated sulfite oxidase deficiency, extensive brain damage in the gray matter and more pronounced damage in the white matter, without subsequent recovery. Early onset of energetic and metabolic imbalance. Impaired energetic status and accumulated metabolites
additional information
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isolated sulfite oxidase deficiency, extensive brain damage in the gray matter and more pronounced damage in the white matter, without subsequent recovery. Early onset of energetic and metabolic imbalance. Impaired energetic status and accumulated metabolites
additional information
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SUOX deficiency is typically inherited as a recessive autosomal trait for which there is no known therapy and typically results in death in infancy
additional information
all of the mutants show decreased rates of intramolecular electron transfer (IET) but increased steady-state rates of catalysis, IET is not the rate determining step for any of the mutations. Redox potentials of wild-tyype and mutant enzymes, overview
additional information
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all of the mutants show decreased rates of intramolecular electron transfer (IET) but increased steady-state rates of catalysis, IET is not the rate determining step for any of the mutations. Redox potentials of wild-tyype and mutant enzymes, overview
additional information
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construction of surface functionalized MoO3 nanoparticles that exhibit an intrinsic biomimetic SuOx activity that allows intracellular oxidation of sulfite to sulfate. Functionalized with a customized bifunctional ligand containing dopamine as anchor group and triphenylphosphonium ion as targeting agent, they selectively target the mitochondria while being highly dispersible in aqueous solutions. Chemically induced sulfite oxidase knockdown cells treated with MoO3 nanoparticles recover their sulfite oxidase activity in vitro, which makes MoO3 nanoparticles a potential therapeutic for sulfite oxidase deficiency and opens new avenues for cost-effective therapies for gene-induced deficiencies. Molybdenum trioxide (MoO3) is a well-known model compound for selective oxidation catalysis. Given their small size and surface-targeting moiety triphenylphosphonium ion (TPP), functionalized MoO3-TPP nanoparticles can cross the cellular membrane and accumulate specifically at the mitochondria, allowing recovery of the SuOx activity of tungstate knockdown human HepG2 hepatoblastoma cells. Steady-state kinetics of MoO3-TPP nanoparticles, a 4fold activity difference between nanoscale and bulkMoO3 indicates the importance of a higher surface area for attaining higher catalytic efficiencies
additional information
mediated electrocatalytic voltammetry of human sulfite oxidase (HSO) is demonstrated with synthetic one electron transfer iron complexes bis(1,4,7-triazacyclononane)iron(III) ([Fe(tacn)2]3+) and 1,2-bis(1,4,7-triaza-1-cyclononyl)ethane iron(III) ([Fe(dtne)]3+) at a glassy carbon working electrode, enzyme-dependent kinetics, overview. The HSO coupled electrode is successfully used for the determination of sulfite concentration in white wine and beer samples, and the results validate with a standard spectrophotometric method
additional information
the specific replacement of the active site Cys207 with selenocysteine during protein expression in Escherichia coli. The sulfite oxidizing activity (kcat/KM) of SeSOMD4Ser is increased at least 1.5fold, and the pH optimum is shifted to a more acidic value compared to those of SOMD4Ser and SOMD4Cys(wt)
additional information
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the specific replacement of the active site Cys207 with selenocysteine during protein expression in Escherichia coli. The sulfite oxidizing activity (kcat/KM) of SeSOMD4Ser is increased at least 1.5fold, and the pH optimum is shifted to a more acidic value compared to those of SOMD4Ser and SOMD4Cys(wt)
additional information
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in tobacco mutants lacking the molybdenum cofactor and, therefore, also lacking active peroxisomal sulfite oxidase, the total sulfite oxidizing capacity of cell extracts decreased to 40% of the wild-type
additional information
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SOX activity in SOX-deficient animals is significantly reduced by 95-99%. In SOX-deficient rats, sulfite treatment causes a significant increase in the plasma lipid hydroperoxide and total oxidant status levels, while -SH content of rat plasma significantly decreases compared to the control. Significant decrease in plasma total antioxidant capacity level by sulfite treatment
additional information
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SOX activity is almost devoid in SOX-deficient rats with respect to controls. In SOX-deficient rats, plasma levels of selenium, iron, and zinc are unaffected by sulfite. Plasma level of Mn is decreasing, while plasma Cu level is increased. Treating SOX-deficient groups with sulfite does not alter plasma level of Mn but makes plasma level of Cu back to its normal level. In SOX-deficient rats, plasma ceruloplasmin ferroxidase activities are lower compared to normal control without sulfite treatment
additional information
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SOX-deficient rats, exposure to sulfite has no effect on hippocampus antioxidant enzymes superoxidase dismutase, catalase, and glutathione peroxidase
