Activating Compound | Comment | Organism | Structure |
---|---|---|---|
cytochrome c | - |
Homo sapiens |
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 | 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 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 | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
mitochondrion | - |
Homo sapiens | 5739 | - |
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 | 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 | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P51687 | - |
- |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
fibroblast | - |
Homo sapiens | - |
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 | Comment | Organism |
---|---|---|
SUOX | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Homo sapiens |
25 | 37 | assay at | Homo sapiens |
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 Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
6 | - |
assay at | Homo sapiens |
7.4 | - |
assay at | Homo sapiens |
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 | 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 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 |