Information on EC 1.6.3.2 - NAD(P)H oxidase (H2O-forming)

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The expected taxonomic range for this enzyme is: Eukaryota, Archaea

EC NUMBER
COMMENTARY hide
1.6.3.2
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RECOMMENDED NAME
GeneOntology No.
NAD(P)H oxidase (H2O-forming)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
2 NAD(P)H + 2 H+ + O2 = 2 NAD(P)+ + 2 H2O
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
non-pathway related
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SYSTEMATIC NAME
IUBMB Comments
NAD(P)H:oxygen oxidoreductase (H2O-forming)
A flavoprotein (FAD). NADPH is a better substrate than NADH [1,3]. By removal of oxygen the enzyme is involved in aerobic tolerance in the thermophilic anaerobic archaeon Thermococcus profundus and in Giardia intestinalis, a microaerophilic single-celled parasite of the order Diplomonadida.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
2 NAD(P)H + H+ + O2
NAD(P)+ + 2 H2O
show the reaction diagram
in anaerobes, flavin-dependent NAD(P)H oxidases play an important role protecting organisms from oxidative stress
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-
?
2 NADH + H+ + O2
NAD+ + 2 H2O
show the reaction diagram
2 NADPH + 2 H+ + O2
2 NADP+ + 2 H2O
show the reaction diagram
3 NADH + 3 H+ + 2 O2
3 NAD+ + H2O
show the reaction diagram
approximately 75% H2O and 25% H2O is produced. Km value of the enzyme towards NADH and NADPH is almost the same whereas specific activity is higher with NADPH compared to NADH
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-
?
3 NADPH + 3 H+ + 2 O2
3 NADP+ + H2O
show the reaction diagram
approximately 87% H2O and 13% H2O2 is produced. Km value of the enzyme towards NADH and NADPH is almost the same whereas specific activity is higher with NADPH compared to NADH
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-
?
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
2 NAD(P)H + H+ + O2
NAD(P)+ + 2 H2O
show the reaction diagram
B2G3S1
in anaerobes, flavin-dependent NAD(P)H oxidases play an important role protecting organisms from oxidative stress
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-
?
2 NADH + H+ + O2
NAD+ + 2 H2O
show the reaction diagram
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reaction is catalyzed by the native dimeric protein under physiological conditions (low amounts of O2) to detoxify O2. Oxidative stress induced conformational change implicates a functional switch of the enzyme. The oxidized enzyme protein can accelerate the aggregation of partially unfolded proteins. It can also bind nucleic acids and produce H2O2 to destroy DNA and RNA with the ultimate function of decreasing cell viability
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?
2 NADPH + 2 H+ + O2
2 NADP+ + 2 H2O
show the reaction diagram
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
NADPH
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
activity is not enhanced by the addition of various heavy metals which suggests that the enzyme does not contain any metal ions as co-factors
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
CuSO4
0.2 mM, 97% inhibition
H2O2
0.5 mM, 50% inhibition
HgCl2
0.5 mM, 80% inhibition
p-chloromercuribenzoate
0.05 mM, complete inhibition
Quinacrine
1 mM, 73% inhibition
Quinine
0.2 mM, 50% inhibition
ZnSO4
0.1 mM, 98% inhibition
additional information
no inhibition by EDTA
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0042 - 0.24
NADH
0.012 - 0.016
NADPH
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
6.2 - 68
NADH
2.5
NADPH
Thermococcus profundus
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pH 7.2, 75C
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
116.9
NADH
Thermococcus profundus
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pH 7.2, 75C
8
206.6
NADPH
Thermococcus profundus
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pH 7.2, 75C
5
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6.5 - 8.5
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pH 6.5: about 70% of maximal activity, pH 8.5: about 45% of maximal activity
7 - 9
active over the range pH 7-9
7.5 - 8.5
pH 7.5: about 70% of maximal activity, pH 8.5: about 70% of maximal activity
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
50 - 70
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50C: about 40% of maximal activity, 70C: about 70% of maximal activity
70 - 80
70C: about 60% of maximal activity, 80C: about 70% of maximal activity
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
45116
1 * 45116, calculated from sequence
46000
1 * 46000, SDS-PAGE
48610
6 * 48610, sequence calculation
49000
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6 * 49000, ring-shaped hexameric form, SDS-PAGE
49375
6 * 49375, mass spectrometry
50000
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2 * 50000, the enzyme exists as a dimeric form under normal/anaerobic conditions, and the dimers assemble into hexamers under stress. H2O2 is the strongest stressor, followed by O2 and cold stress, SDS-PAGE; 6 * 50000, the enzyme exists as a dimeric form under normal/anaerobic conditions, and the dimers assemble into hexamers under stress. H2O2 is the strongest stressor, followed by O2 and cold stress, SDS-PAGE
300000
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dimer
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2 * 50000, the enzyme exists as a dimeric form under normal/anaerobic conditions, and the dimers assemble into hexamers under stress. H2O2 is the strongest stressor, followed by O2 and cold stress, SDS-PAGE
hexamer
monomer
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
100
150 min, less than 5% loss of activity
120
secondary structure of the enzyme is not stable at this temperature
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
wild-type and mutant enzymes
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
C122A
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mutant contains tightly bound FAD. Mutant has similar NADH and NADPH oxidase activity to that of the wild-type protein
C45A
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mutant contains tightly bound FAD. Mutant has less than 10% of the NAD(P)H oxidase activity of the wild-type protein. Mutation alters the reaction to produce H2O2 instead of H2O
C45A/C122A
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mutant contains tightly bound FAD. Mutant has less than 10% of the NAD(P)H oxidase activity of the wild-type protein. Mutation alters the reaction to produce H2O2 instead of H2O