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Literature summary extracted from

  • Kodali, V.K.; Thorpe, C.
    Quiescin sulfhydryl oxidase from Trypanosoma brucei: catalytic activity and mechanism of a QSOX family member with a single thioredoxin domain (2010), Biochemistry, 49, 2075-2085.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
1.8.3.2 expression in Escherichia coli Trypanosoma brucei

Protein Variants

EC Number Protein Variants Comment Organism
1.8.3.2 C69S about 5% of wild-type activity with substrate dithiothreitol, 0.5% with substrate rRNase Trypanosoma brucei
1.8.3.2 C72S about 5% of wild-type activity with substrate dithiothreitol, 0.5% with substrate rRNase Trypanosoma brucei
1.8.3.2 additional information replacement of either cysteine of the proximal disulfide, i.e. CIII or CIV with serine essentially abolishes activity both towards dithiothreitol and rRNase. Mutations of the terminal CxxC disulfide do not show significant loss of activity towards dithiothreitol or rRNase, the visible spectra of both CVS and CVIS mutants are comparable to that of the wild-type protein Trypanosoma brucei

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.8.3.2 0.086
-
 dithiothreitol pH 7.5, 37°C Trypanosoma brucei
1.8.3.2 0.36
-
 rRNaseA pH 7.5, 37°C Trypanosoma brucei

Localization

EC Number Localization Comment Organism GeneOntology No. Textmining
1.8.3.2 membrane type I membrane protein Trypanosoma brucei 16020
-

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
1.8.3.2 54000
-
 PAGE Trypanosoma brucei
1.8.3.2 54300
-
 analytical ultracentrifugation Trypanosoma brucei

Organism

EC Number Organism UniProt Comment Textmining
1.8.3.2 Trypanosoma brucei Q585M6
-
-

Storage Stability

EC Number Storage Stability Organism
1.8.3.2 -20°C, 50 mM potassium phosphate buffer containing 1 mM EDTA, pH 7.5, stable for at least 1 year Trypanosoma brucei
1.8.3.2 4°C, 50 mM potassium phosphate buffer containing 1 mM EDTA, pH 7.5, stable for at least 6 months Trypanosoma brucei

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.8.3.2 2 dithiothreitol + O2
-
 Trypanosoma brucei dithiothreitol disulfide + H2O2
-
 ?
1.8.3.2 2 glutathione + O2
-
 Trypanosoma brucei glutathione disulfide + H2O2
-
 ?
1.8.3.2 additional information unfolded reduced proteins are more than 200fold more effective substrates on a per-thiol basis than glutathione, and some 10fold better than the parasite bis-glutathione analog, trypanothione. The CxxC motif in the single Trx domain is crucial for efficient catalysis of the oxidation of both reduced RNase and the model substrate dithiothreitol. The proximal disulfide CIII-CIV, which interacts with the flavin, is catalytically crucial. Turnover is limited by an internal redox step leading to 2-electron reduction of the FAD cofactor Trypanosoma brucei ?
-
 ?
1.8.3.2 rRNaseA + O2
-
 Trypanosoma brucei ? + H2O2
-
 ?

Subunits

EC Number Subunits Comment Organism
1.8.3.2 monomer 1 * 54000, SDS-PAGE Trypanosoma brucei

Synonyms

EC Number Synonyms Comment Organism
1.8.3.2 QSOX
-
 Trypanosoma brucei
1.8.3.2 quiescin sulfhydryl oxidase
-
 Trypanosoma brucei

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1.8.3.2 22
-
 rRNaseA pH 7.5, 37°C Trypanosoma brucei
1.8.3.2 45
-
 dithiothreitol pH 7.5, 37°C Trypanosoma brucei

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
1.8.3.2 7
-
-
 Trypanosoma brucei

Cofactor

EC Number Cofactor Comment Organism Structure
1.8.3.2 FAD turnover is limited by an internal redox step leading to 2-electron reduction of the FAD cofactor Trypanosoma brucei

kcat/KM [mM/s]

EC Number kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
1.8.3.2 2.3
-
 glutathione pH 7.5, 37°C Trypanosoma brucei
1.8.3.2 180
-
 rRNaseA pH 7.5, 37°C Trypanosoma brucei
1.8.3.2 230
-
 dithiothreitol pH 7.5, 37°C Trypanosoma brucei