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Literature summary for 1.8.3.1 extracted from

  • Wang, J.; Krizowski, S.; Fischer-Schrader, K.; Niks, D.; Tejero, J.; Sparacino-Watkins, C.; Wang, L.; Ragireddy, V.; Frizzell, S.; Kelley, E.E.; Zhang, Y.; Basu, P.; Hille, R.; Schwarz, G.; Gladwin, M.T.
    Sulfite oxidase catalyzes single-electron transfer at molybdenum domain to reduce nitrite to nitric oxide (2015), Antioxid. Redox Signal., 23, 283-294 .
    View publication on PubMedView publication on EuropePMC

Activating Compound

Activating Compound Comment Organism Structure
cytochrome c
-
Homo sapiens

Cloned(Commentary)

Cloned (Comment) Organism
recombinant expression of wild-type and mutant enzymes in Escherichia coli strain Escherichia coli TP1000 cells, specific replacement of the active site Cys207 with selenocysteine during protein expression in Escherichia coli Homo sapiens

Protein Variants

Protein Variants Comment Organism
C242S/C253S/C260S/C451S site-directed mutagenesis, mutation of the four active site Cys residues Homo sapiens
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) Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information steady-state kinetics Homo sapiens
additional information
-
additional information kinetics of sulfite oxidase-dependent nitrite reduction, the catalyzes single-electron transfer is similar to Michaelis-Menten kinetics Homo sapiens
0.004
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
0.0042
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
0.0048
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
0.0062
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
0.0079
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
0.0082
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
0.0096
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
0.0107
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
0.0121
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant wild-type enzyme Homo sapiens
0.0146
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
0.0166
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant wild-type enzyme Homo sapiens
0.0174
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
0.019
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
0.0196
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant wild-type enzyme Homo sapiens
0.0288
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion
-
Homo sapiens 5739
-

Metals/Ions

Metals/Ions Comment Organism Structure
Fe3+
-
Homo sapiens
Molybdenum
-
Homo sapiens
Molybdenum active site bound to the dithiolene sulfurs of one molybdopterin (MPT) molecule, carrying two oxygen ligands, and is further coordinated by the thiol sulfur of a conserved cysteine residue Homo sapiens
additional information the SO Moco binding domain has the ability to oxidize sulfite in the presence of artificial electron acceptors like ferricyanide. The two-electron oxidation of sulfite to sulfate occurs at the molybdenum site, which is reduced from Mo(VI) to Mo(IV), followed by intramolecular electron transfer to the cytb5 site, with cytochrome c serving as the terminal electron acceptor Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
sulfite + O2 + H2O Homo sapiens
-
sulfate + H2O2
-
?
sulfite + O2 + H2O Homo sapiens sulfite is the physiological substrate sulfate + H2O2
-
?

Organism

Organism UniProt Comment Textmining
Homo sapiens P51687
-
-

Source Tissue

Source Tissue Comment Organism Textmining
fibroblast
-
Homo sapiens
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
additional information reduced sulfite oxidase catalyzes single-electron transfer at molybdenum domain to reduce nitrite to nitric oxide. At physiological concentrations of nitrite, sulfite oxidase functions as nitrite reductase in the presence of a one-electron donor, exhibiting redox coupling of substrate oxidation and nitrite reduction to form NO. With sulfite, the physiological substrate, sulfite oxidase only facilitates one turnover of nitrite reduction. Nitrite reduction occurs at the molybdenum center via coupled oxidation of Mo(IV) to Mo(V). Reaction rates of nitrite to NO decreased in the presence of a functional heme domain, mediated by steric and redox effects of this domain. Nitrite binds to and is reduced at the molybdenum site of mammalian sulfite oxidase, which may be allosterically regulated by heme and molybdenum domain interactions, and contributes to the mammalian nitrate-nitrite-NO signaling pathway in human fibroblasts. Using phenosafranine or sulfite as reducing substrate, the Mo-domain shows much faster nitrite reduction to NO than holo-sulfite oxidase, catalytic Mo(IV) to Mo(V) nitrite reduction cycle, overview Homo sapiens ?
-
?
additional information the sulfite oxidase catalyzes single-electron transfer at molybdenum domain to reduce nitrite to nitric oxide. The SO Moco binding domain has the ability to oxidize sulfite in the presence of artificial electron acceptors like ferricyanide. The two-electron oxidation of sulfite to sulfate occurs at the molybdenum site, which is reduced from Mo(VI) to Mo(IV), followed by intramolecular electron transfer to the cytb5 site, with cytochrome c serving as the terminal electron acceptor. The movement of domains between the Moco domain and the cytb5 domain facilitated by the flexible linker is essential for efficient electron transfer between the heme and the Moco Homo sapiens ?
-
?
sulfite + ferricyanide + H+
-
Homo sapiens sulfate + reduced ferricyanide
-
?
sulfite + O2 + H2O
-
Homo sapiens sulfate + H2O2
-
?
sulfite + O2 + H2O sulfite is the physiological substrate Homo sapiens sulfate + H2O2
-
?
sulfite + O2 + H2O during the sulfite-sulfite oxidase-cytochrome c catalytic cycle, movement between the molybdenum and heme domain is required to enable efficient single-electron transfer from molybdenum via the heme b5 cofactor to cytochrome c Homo sapiens sulfate + H2O2
-
?

Synonyms

Synonyms Comment Organism
SUOX
-
Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
25
-
assay at Homo sapiens
25 37 assay at Homo sapiens

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
9.4
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
13.9
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant wild-type enzyme Homo sapiens
16.2
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
19.8
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
20.8
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
25.8
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
26.1
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
27.3
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant wild-type enzyme Homo sapiens
31.8
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
32.4
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant wild-type enzyme Homo sapiens
36.2
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
37.7
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
41.2
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
46.6
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
6
-
assay at Homo sapiens
7.4
-
assay at Homo sapiens

Cofactor

Cofactor Comment Organism Structure
cytochrome b5
-
Homo sapiens
cytochrome c
-
Homo sapiens
molybdenum cofactor
-
Homo sapiens
additional information during the sulfite-sulfite oxidase-cytochrome c catalytic cycle, movement between the molybdenum and heme domain is required to enable efficient single-electron transfer from molybdenum via the heme b5 cofactor to cytochrome c. Using phenosafranine or sulfite as reducing substrate, the Mo-domain shows much faster nitrite reduction to NO than holo-sulfite oxidase Homo sapiens

General Information

General Information Comment Organism
additional information the catalytic site of SO consists of a molybdenum ion bound to the dithiolene sulfurs of one molybdopterin (MPT) molecule, carrying two oxygen ligands, and is further coordinated by the thiol sulfur of a conserved cysteine residue Homo sapiens
physiological function sulfite oxidase (SO) is an essential molybdoenzyme for humans, catalyzing the final step in the degradation of sulfur-containing amino acids and lipids, which is the oxidation of sulfite to sulfate Homo sapiens
physiological function sulfite oxidase significantly contributes to hypoxic nitrite signaling as demonstrated by activation of the canonical NO-sGCcGMP pathway Homo sapiens

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
979
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
1139
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant wild-type enzyme Homo sapiens
1257
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
1374
-
sulfite with ferricanide, pH 6.0, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
1615
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant wild-type enzyme Homo sapiens
1828
-
sulfite with ferricanide, pH 8.9, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
1952
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant wild-type enzyme Homo sapiens
2411
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
2822
-
sulfite with ferricanide, pH 8.4, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
3194
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
4050
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
4125
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant mutant C242S/C253S/C260S/C451S Homo sapiens
4598
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens
4952
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant wild-type enzyme Homo sapiens
5899
-
sulfite with ferricanide, pH 7.1, 25°C, recombinant selenomethionine-labeled mutant C242S/C253S/C260S/C451S Homo sapiens