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1.17.3.2: xanthine oxidase

This is an abbreviated version!
For detailed information about xanthine oxidase, go to the full flat file.

Word Map on EC 1.17.3.2

Reaction

xanthine
+
H2O
 +
O2
=
Urate
 +
H2O2

Synonyms

AXOR, EC 1.1.3.22, EC 1.2.3.2, EC 1.2.3.2., hypoxanthine oxidase, hypoxanthine-xanthine oxidase, hypoxanthine:oxygen oxidoreductase, More, oxidase, xanthine, Schardinger enzyme, xanthine dehydrogenase/oxidase, xanthine oxidase, xanthine oxidoreductase, xanthine: oxygen oxidoreductase, xanthine:O2 oxidoreductase, xanthine:oxygen oxidoreductase, xanthine:xanthine oxidase, XnOx, XO, XOD, XOR

ECTree

     1 Oxidoreductases
         1.17 Acting on CH or CH2 groups
             1.17.3 With oxygen as acceptor
                1.17.3.2 xanthine oxidase

pH Range

pH Range on EC 1.17.3.2 - xanthine oxidase

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pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5 - 9
-
pH 5.0: about 10% of activity maximum, pH 9.0: about 25% of activity maximum
6 - 7.6
-
under aerobic conditions, NO generation increases more than three times as the pH value decreases from pH 7.4 to 6.0
6 - 9
6.5 - 9.5
-
pH 6.5: about 40% of maximal activity, pH 9.5: about 65% of maximal activity, conversion of dibromoacetonitrile to CN-
7.5 - 9.5
potassium phosphate, Tris-HCl, Tris-acetate and glycine-NaOH buffer
7.7 - 9.1
-
at pH 7.7 and 9.1: about 30% of activity maximum
additional information
comparison of the pH dependence of both kred and kred/Kd from reductive half-reaction experiments between wild-type enzyme and mutant E232Q, overview. The ionized Glu232 of wild-type enzyme plays an important role in catalysis by discriminating against the monoanionic form of substrate, effectively increasing the pKa of the substrate by two pH units and ensuring that at physiological pH the neutral form of the substrate predominates in the Michaelis complex