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Literature summary for 1.8.5.6 extracted from

  • Boughanemi, S.; Infossi, P.; Giudici-Orticoni, M.T.; Schoepp-Cothenet, B.; Guiral, M.
    Sulfite oxidation by the quinone-reducing molybdenum sulfite dehydrogenase SoeABC from the bacterium Aquifex aeolicus (2020), Biochim. Biophys. Acta, 1861, 148279 .
    View publication on PubMed

Cloned(Commentary)

Cloned (Comment) Organism
sequence comparisons and phylogenetic analysis Aquifex aeolicus

Inhibitors

Inhibitors Comment Organism Structure
2-heptyl-4-hydroxyquinoline N-oxide HQNO, complete inhibition at 0.01 mM Aquifex aeolicus
antimycin A 55% inhibition at 0.027 mM Aquifex aeolicus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information Michaelis-Menten kinetics Aquifex aeolicus
0.0026
-
sulfite pH 8.3, 55°C, with decyl-ubiquinone Aquifex aeolicus
0.034
-
sulfite pH 8.3, 55°C, with Nitro-blue tetrazolium Aquifex aeolicus

Localization

Localization Comment Organism GeneOntology No. Textmining
membrane the enzyme is membrane-bound and quinone reactive (via the SoeC subunit), facing the cytoplasm where SoeB (a module that carries FeeS centers) and the SoeA (the Mo-carrying catalytic subunit) are exposed. The enzyme is a large membrane-bound complex, formerly called SreABC Aquifex aeolicus 16020
-

Metals/Ions

Metals/Ions Comment Organism Structure
Molybdenum required, enzyme Soe contains, in its active site, a molybdenum atom coordinated by two molecules of pyranopterin guanosine dinucleotide (therefore also named Mo-bisPGD enzymes) rather than a single pyranopterin Aquifex aeolicus

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
211000
-
monomeric trimer, gel filtration Aquifex aeolicus
389000
-
dimeric trimer, gel filtration Aquifex aeolicus

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
sulfite + decyl-ubiquinone + H2O Aquifex aeolicus
-
sulfate + decyl-ubiquinol
-
r

Organism

Organism UniProt Comment Textmining
Aquifex aeolicus O67280 AND O67279 AND O67278 subunits SreA, SreB, and SreC
-

Purification (Commentary)

Purification (Comment) Organism
native enzyme 23fold from cell membranes via solubilization by various non-ionic detergents, centrifugation at 40000 x g, followed by anion exchange chromatography, ultrafiltration, and gel filtration Aquifex aeolicus

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
84.2
-
purified enzyme, substrate sulfite, pH 8.3, 55°C Aquifex aeolicus

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
additional information the enzyme catalyzes sulfite oxidation using Nitro-blue tetrazolium as artificial electron acceptor at pH 7.8 and 60°C. The enzyme specifically oxidizes sulfite but can work in the reverse direction, reduction of sulfur or tetrathionate, using reduced methyl viologen (MV) as electron donor, thiosulfate is not able to act as an electron acceptor from MV, absence of reduction of thiosulfate by SoeABC. Oxidation of sodium tetrathionate by SoeABC is performed using DCPIP (2,6-dichlorophenolindophenol) in the presence or absence of phenazine methosulfate (PMS). No oxidation of sulfite, tetrathionate, polysulfide or thiosulfate, SoeABC seems therefore to oxidize sulfite specifically Aquifex aeolicus ?
-
-
sulfite + decyl-ubiquinone + H2O
-
Aquifex aeolicus sulfate + decyl-ubiquinol
-
r
sulfur + reduced methyl viologen + H2O
-
Aquifex aeolicus H2S + oxidized methyl viologen
-
?
tetrathionate + reduced methyl viologen + H2O
-
Aquifex aeolicus ? + oxidized methyl viologen
-
?

Subunits

Subunits Comment Organism
hexamer dimer of trimer (alphabetagamma)2 Aquifex aeolicus

Synonyms

Synonyms Comment Organism
quinone-reducing molybdenum sulfite dehydrogenase
-
Aquifex aeolicus
SoeABC
-
Aquifex aeolicus
SreABC
-
Aquifex aeolicus
sulfur reductase
-
Aquifex aeolicus

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
55
-
oxidation reaction Aquifex aeolicus
55 70 reduction reaction Aquifex aeolicus

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
52.9
-
sulfite pH 8.3, 55°C, with decyl-ubiquinone Aquifex aeolicus
567
-
sulfite pH 8.3, 55°C, with Nitro-blue tetrazolium Aquifex aeolicus

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7.8
-
cell membrane fraction, assay at Aquifex aeolicus
8.2
-
purified enzyme, reduction assay at Aquifex aeolicus
8.3
-
purified enzyme, oxidation reaction Aquifex aeolicus

Cofactor

Cofactor Comment Organism Structure
molybdenum cofactor enzyme Soe contains, in its active site, a molybdenum atom coordinated by two molecules of pyranopterin guanosine dinucleotide (therefore also named Mo-bisPGD enzymes) rather than a single pyranopterin Aquifex aeolicus

General Information

General Information Comment Organism
evolution phylogenetic tree of Mo-bisPGD enzymes involved in sulfur compounds conversion, phylogenetic analysis, overview Aquifex aeolicus
metabolism SoeABC is involved in the sulfite oxidation in the marine hyperthermophilic bacterium Aquifex aeolicus Aquifex aeolicus
additional information the SoeABC enzyme is a member of the DMSO-reductase family of molybdenum enzymes, or complex iron-sulfur molybdoenzymes (CISM) family Aquifex aeolicus
physiological function electrons generated by sulfite oxidation in the cytoplasm enter the respiratory chain at the level of quinones Aquifex aeolicus

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
16676.5
-
sulfite pH 8.3, 55°C, with Nitro-blue tetrazolium Aquifex aeolicus
20346
-
sulfite pH 8.3, 55°C, with decyl-ubiquinone Aquifex aeolicus