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Enzyme Nomenclature
Information on EC 1.6.5.5 - NADPH:quinone reductase
Word Map on EC 1.6.5.5
- 1.6.5.5
- lens
- fmn
-
two-electron
- camel
- semiquinone
-
nadph:menadione
-
nadph:quinone-acceptor
-
pentaerythritol
-
tetranitrate
-
1.6.99.2
- 9,10-phenanthrenequinone
- dicumarol
-
alpha,beta-unsaturated
- 2,4,6-trinitrotoluene
-
taxon-specific
-
bioreduction
-
nadph-quinone
- morphinone
-
explosives
-
massey
-
enones
-
lens-specific
- p-hydroxybenzaldehyde
-
camelids
- 2-methyl-1,4-naphthoquinone
-
12-oxophytodienoate
- medicine
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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria
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EC NUMBER 
COMMENTARY 
1.6.5.5
-
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RECOMMENDED NAME
GeneOntology No.
NADPH:quinone reductase
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone
enzyme acts through a one-electron transfer process
-
NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone
reaction with 2,6-dichlorophenolindophenol and NADPH proceeds through a ping-pong mechanism
-
NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone
reaction with 9,10-phenanthrenequinone and NADPH proceeds through a ping-pong mechanism
-
NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone
ping pong reaction mechanism
-
NADPH + H+ + 2 quinone = NADP+ + 2 semiquinone
-
-
-
-
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oxidation
-
-
-
-
reduction
-
-
-
-
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SYSTEMATIC NAME
IUBMB Comments
NADPH:quinone oxidoreductase
A zinc enzyme, specific for NADPH. Catalyses the one-electron reduction of certain quinones, with the orthoquinones 1,2-naphthoquinone and 9,10-phenanthrenequinone being the best substrates [1]. Dicoumarol [cf. EC 1.6.5.2 NAD(P)H dehydrogenase (quinone)] and nitrofurantoin are competitive inhibitors with respect to the quinone substrate. The semiquinone free-radical product may be non-enzymically reduced to the hydroquinone or oxidized back to quinone in the presence of O2 [1]. In some mammals, the enzyme is abundant in the lens of the eye, where it is identified with the protein zeta-crystallin.
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CAS REGISTRY NUMBER
COMMENTARY
9032-20-6
-
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
physiological function
-
ArsH plays a role in the response to oxidative stress caused by arsenite
additional information
-
in silico structural model of ArsH reconstituted with FMN, overview
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
1,2-naphthoquinone + NADPH + H+
1,2-naphthosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
1,2-naphthoquinone + NADPH + H+
? + NADP+
-
the activity with 9,10-phenanthrenequinone and with 1,2-naphthoquinone is equal
-
-
?
1,4-benzoquinone + NADPH + H+
1,4-benzosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
1,4-naphthoquinone + NADPH + H+
1,4-naphthosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 1,2-naphthoquinone + NADPH + H+
2 1,2-naphthosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 1,2-naphthoquinone + NADPH + H+
? + NADP+
-
the activity with 9,10-phenanthrenequinone and with 1,2-naphthoquinone is equal
-
-
?
2 1,4-benzoquinone + NADPH + H+
2 1,4-benzosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 1,4-naphthosemiquinone + NADPH + H+
2 1,4-naphthosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 5-hydroxy-1,4-naphthoquinone + NADPH + H+
2 5-hydroxy-1,4-naphthosemiquinone + NADP+
-
i.e. juglone. Production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 5-hydroxy-2-methyl-1,4-naphthoquinone + NADPH + H+
5-hydroxy-2-methyl-1,4-naphthoquinone + NADP+
-
i.e. plumbagin. Production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 9,10-phenanthrenequinone + NADPH + H+
? + NADP+
-
70% of the activity with 9,10-phenanthrenequinone
-
-
?
2 decyl-plastoquinone + NADPH + H+
2 decyl-plastosemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
5-hydroxy-1,4-naphthoquinone + NADPH + H+
5-hydroxy-1,4-naphthosemiquinone + NADP+
-
i.e. juglone. Production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
5-hydroxy-2-methyl-1,4-naphthoquinone + NADPH
5-hydroxy-2-methyl-1,4-naphthoquinol + NADP+
-
i.e. plumbagin, 0.9% of the activity with 1,2-naphthoquinone
-
-
-
5-hydroxy-2-methyl-1,4-naphthoquinone + NADPH + H+
5-hydroxy-2-methyl-1,4-naphthosemiquinone + NADP+
-
i.e. plumbagin. Production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
9,10-phenanthrenequinone + NADPH + H+
9,10-phenanthrenequinol + NADP+
Q7A492
one-electron reduction mechanism. Concomitantly with NADPH consumption, generation of superoxide is observed
-
-
?
9,10-phenanthrenequinone + NADPH + H+
9,10-phenanthrenesemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
9,10-phenanthrenequinone + NADPH + H+
? + NADP+
-
the activity with 9,10-phenanthrenequinone and with 1,2-naphthoquinone is equal
-
-
?
methyl-1,4-benzoquinone + NADPH
methyl-1,4-benzoquinol + NADP+
-
20.6% of the activity with 1,2-naphthoquinone
-
-
-
NADPH + H+ + 2 2,5-dimethyl-4-benzoquinone
NADP+ + 2 2,5-dimethyl-4-benzosemiquinone
-
-
-
-
?
NADPH + H+ + 2 2-hydroxy-1,4-naphthoquinone
NADP+ + 2 2-hydroxy-1,4-naphthosemiquinone
-
-
-
-
?
NADPH + H+ + 2 dibromothymoquinone
NADP+ + 2 dibromothymosemiquinone
-
-
-
-
?
NADPH + H+ + komaroviquinone
NADP+ + ?
-
reduction of komaroviquinone to its semiquinone radical. Antichagasic activity of komaroviquinone is due to generation of reactive oxygen species catalyzed by Trypanosoma cruzi old yellow enzyme
-
-
?
NADPH + H+ + oxidized 2,6-dichlorophenolindophenol
NADP+ + reduced 2,6-dichlorophenolindophenol
1,4-benzoquinone + NADPH
1,4-benzoquinol + NADP+
-
15.3% of the activity with 1,2-naphthoquinone
-
-
-
1,4-naphthoquinone + NADPH
1,4-naphthoquinol + NADP+
-
2.6% of the activity with 1,2-naphthoquinone
-
-
-
2 9,10-phenanthrenequinone + NADPH + H+
2 9,10-phenanthrenesemiquinone + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
2 9,10-phenanthrenequinone + NADPH + H+
2 9,10-phenanthrenesemiquinone + NADP+
-
very strong reduction activity towards large substrates such as 9,10-phenanthrenequinone. The zeta-crystallin-like quinone oxidoreductase catalyzes one-electron reduction of certain quinones to generate semiquinone
-
-
?
5-hydroxy-1,4-naphthoquinone + NADPH
5-hydroxy-1,4-naphthoquinol + NADP+
-
-
-
-
-
5-hydroxy-1,4-naphthoquinone + NADPH
5-hydroxy-1,4-naphthoquinol + NADP+
-
i.e. juglone, 12.5% of the activity with 1,2-naphthoquinone
-
-
-
9,10-phenanthrenequinone + NADPH
9,10-phenanthrenequinol + NADP+
-
-
-
-
-
9,10-phenanthrenequinone + NADPH
9,10-phenanthrenequinol + NADP+
-
best substrate
-
-
-
9,10-phenanthrenequinone + NADPH
9,10-phenanthrenequinol + NADP+
-
50% of the activity with 1,2-naphthoquinone
-
-
-
dichlorophenolindophenol + NADPH + H+
reduced dichlorophenolindophenol + NADP+
-
-
-
-
?
dichlorophenolindophenol + NADPH + H+
reduced dichlorophenolindophenol + NADP+
-
production of semiquinone by univalent catalysts is detectable by the reduction of ferricytochrome c by the semiquinone to ferrocytochrome c
-
-
?
menadione + NADPH + H+
menadiol + NADP+
-
-
under aerobic conditions, menadiol is readily oxidized to menadione by two 1-electron steps producing the semiquinone and the parent quinone with concomitant production of superoxide anion, which leads to generation of hydroxyl radicals
-
?
NADPH + H+ + 2 quinone
NADP+ + 2 semiquinone
-
the catalytic cycle of ArsH consists of the acceptance of two electrons from NADPH to reduce the flavin cofactor (reductive half-reaction) and the transfer of these electrons to an acceptor (oxidative half-reaction)
-
-
?
NADPH + H+ + oxidized 2,6-dichlorophenolindophenol
NADP+ + reduced 2,6-dichlorophenolindophenol
-
-
-
-
-
NADPH + H+ + oxidized 2,6-dichlorophenolindophenol
NADP+ + reduced 2,6-dichlorophenolindophenol
-
-
-
-
-
NADPH + H+ + oxidized 2,6-dichlorophenolindophenol
NADP+ + reduced 2,6-dichlorophenolindophenol
-
3.8% of the activity with 1,2-naphthoquinone
-
-
-
additional information
?
-
-
no activity with: phylloquinone (vitamin K1), menaquinone (vitamin K2), menadione (vitamin K3) and ferricyanide. Preference for o-quinones over p-quinones, and the inability to recognize menadione and ferricyanide as substrates, clearly distinguishe P1-ZCr and guinea-pig ZCr from the flavin-containing NAD(P)H-quinone oxidoreductases in plants and animals. P1-ZCr also catalyzed the divalent reduction of diamide to 1,2-bis(N,N-dimethylcarbamoyl)hydrazine, with a kcat comparable with that for quinones. Two other azodicarbonyl compounds also served as substrates of P1-ZCr. Guinea-pig ZCr, however, did not catalyze the azodicarbonyl reduction. Hence, plant ZCr is distinct from mammalian ZCr, and can be referred to as NADPH:azodicarbonyl/quinone reductase. The quinone-reducing reaction is accompanied by radical chain reactions to produce superoxide radicals, while the azodicarbonyl reducing reaction is not
-
-
-
additional information
?
-
-
no activity with menadione and 9,10-anthraquinone
-
-
-
additional information
?
-
-
inactive with: menadione, ubiquinone, 9,10-anthraquinone, vitamin K1, vitamin K2
-
-
-
additional information
?
-
-
although in the lens the enzyme is considered to be a crystallin, or lens structural protein, because of its high abundance its enzymatic activity and expression at catalytic levels in other tissues of various species suggest that it has a fundamental physiological role outside the lens, perhaps in the detoxification of xenobiotics
-
-
-
additional information
?
-
-
no activity with: phylloquinone (vitamin K1), menaquinone (vitamin K2), menadione (vitamin K3), ferricytochrome and ferricyanide. Preference for o-quinones over p-quinones, and the inability to recognize menadione and ferricyanide as substrates, clearly distinguishe Arabidopsis thaliana P1-ZCr and guinea-pig ZCr from the flavin-containing NAD(P)H-quinone oxidoreductases in plants and animals
-
-
-
additional information
?
-
-
although in the lens the enzyme is considered to be a crystallin, or lens structural protein, because of its high abundance its enzymatic activity and expression at catalytic levels in other tissues of various species suggest that it has a fundamental physiological role outside the lens, perhaps in the detoxification of xenobiotics
-
-
-
additional information
?
-
-
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
-
-
-
additional information
?
-
-
enzyme reduces ortho-quinones in the presence of NADPH but is not active with 2-alkenals
-
-
-
additional information
?
-
-
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
-
-
-
additional information
?
-
-
enzyme reduces ortho-quinones in the presence of NADPH but is not active with 2-alkenals
-
-
-
additional information
?
-
-
although the enzyme is able to stabilize the anionic semiquinone form of the FMN, reduction of quinones involves the hydroquinone form of the flavin cofactor, and the enzymatic reaction occurs through a ping pong-type mechanism. ArsH is able to catalyze one-electron reactions (oxygen and cytocrome c reduction), involving the FMN semiquinone form, but with lower efficiency
-
-
-
additional information
?
-
QR1 catalyzes the univalent reduction of quinones to semiquinone radicals
-
-
-
additional information
?
-
-
QR1 catalyzes the univalent reduction of quinones to semiquinone radicals
-
-
-
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
additional information
?
-
-
although in the lens the enzyme is considered to be a crystallin, or lens structural protein, because of its high abundance its enzymatic activity and expression at catalytic levels in other tissues of various species suggest that it has a fundamental physiological role outside the lens, perhaps in the detoxification of xenobiotics
-
-
-
additional information
?
-
-
although in the lens the enzyme is considered to be a crystallin, or lens structural protein, because of its high abundance its enzymatic activity and expression at catalytic levels in other tissues of various species suggest that it has a fundamental physiological role outside the lens, perhaps in the detoxification of xenobiotics
-
-
-
additional information
?
-
-
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
-
-
-
additional information
?
-
-
the human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding proteins and that this property has been conserved in zeta-crystallins throughout evolution. This supports a role for zeta-crystallins as trans-acting factors that could regulate the turnover of certain mRNAs
-
-
-
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
NADPH
NADPH is located in the cleft between domains I and II. The adenine ring is sandwiched between the main chains of Ala220 and Glu221 and the side chain of Arg292. Ala220 and Glu221 are disordered in apo-QOR
NADPH
-
NADPH binding causes conformational changes in the structure of the enzyme
NADPH
-
NADPH, but not NADH, competitively prevents binding of zeta-crystallin to RNA, suggesting that the cofactor-binding site is involved in RNA binding
NADPH
interference of NADPH on Zta1p binding to RNA is much lower than that of NADPH on human zeta-crystallin, consistent with a weaker binding of NADPH to the yeast enzyme
NADPH
-
specificity to NADPH, as judged by kcat/Km, is more than 1000fold higher than that to NADH
additional information
Q7A492
no cofactor: NADH. Sequence does not contain a flavin-binding motif
-
additional information
-
no cofactor: NADH. Sequence does not contain a flavin-binding motif
-
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
2,5-Dichloro-3,6-dihydroxy-1,4-benzoquinone
-
i.e. chloranilic acid, noncompetitive with respect to both NADPH and 9,10-phenanthrenequinone
4-chloromercuribenzoate
-
both NADPH and NADP1 suppress the inhibition, but NADH does not
4-Hydroxycoumarin
-
reversible time-independent inhibition. Only dicoumarol, 4-hydroxycoumarin and warfarin inhibit in micromolar ranges. 7-Hydroxy-4-methylcoumarin is ineffective. Competitive inhibition with respect to 2,6-dichlorophenolindophenol, uncompetitive with respect to NADPH. Phenolic hydroxyl group at the C-4 position in the coumarin skeleton is important for the maximal inhibition. Sequence of potency for the inhibitors in descending order: dicoumarol, 4-hydroxycoumarin, warfarin, coumarin
coumarin
-
reversible time-independent inhibition. Only dicoumarol, 4-hydroxycoumarin and warfarin inhibit in micromolar ranges. 7-Hydroxy-4-methylcoumarin is ineffective. Competitive inhibition with respect to 2,6-dichlorophenolindophenol, uncompetitive with respect to NADPH. Phenolic hydroxyl group at the C-4 position in the coumarin skeleton is important for the maximal inhibition. Sequence of potency for the inhibitors in descending order: dicoumarol, 4-hydroxycoumarin, warfarin, coumarin
N-ethylmaleimide
-
both NADPH and NADP1 suppress the inhibition, but NADH does not
pyridoxal-5'-phosphate
-
inactivation follows pseudo-first-order kinetics. NADPH protects against inactivation, 9,10-phenanthrenequinone does not protect. Inhibition is uncompetitive with NADPH and non-competitive with respect to 9,10-phenanthrenequinone
5,5'-dithiobis(2-nitrobenzoate)
-
inactivation is caused by a modification of one Cys per subunit, reactivation by dithiothreitol or KCN. NADPH partially protects from inactivation, 9,10-phenanthrenequinone enhances the modification
Cibacron blue 3GA
-
inhibits the reaction with NADPH and 9,10-phenanthrenequinone. Linear mixed type inhibition with respect to NADPH and noncompetitive with respect to 9,10-phenanthrenequinone
dicoumarol
-
competitive with respect to 2,6-dichlorophenol-indophenol, uncompetitive with respect to NADPH
dicoumarol
-
reversible time-independent inhibition. Only dicoumarol, 4-hydroxycoumarin and warfarin inhibit in micromolar ranges. 7-Hydroxy-4-methylcoumarin is ineffective. Competitive inhibition with respect to 2,6-dichlorophenolindophenol, uncompetitive with respect to NADPH. Phenolic hydroxyl group at the C-4 position in the coumarin skeleton is important for the maximal inhibition.Sequence of potency for the inhibitors in descending order: dicoumarol, 4-hydroxycoumarin, warfarin, coumarin
dicoumarol
-
presence of dicoumarol decreases the production of hydroxyl radical and attenuates DNA strand-breaks in MCF-7 cells treated with menadione
dithiothreitol
-
inhibition is completely prevented by preincubation with 9,10-phenanthrenequinone but not by NADPH
dithiothreitol
-
strong competitive inhibition with respect to 9,10-phenanthrenequinone
NADP+
-
mixed-type inhibition with respect to NADPH, competitive with respect to 9,10-phenanthrenequinone
NADP+
-
can act as a competitive inhibitor for NADPH binding at the active site of an enzyme
warfarin
-
reversible time-independent inhibition. Only dicoumarol, 4-hydroxycoumarin and warfarin inhibit in micromolar ranges. 7-Hydroxy-4-methylcoumarin is ineffective. Competitive inhibition with respect to 2,6-dichlorophenolindophenol, uncompetitive with respect to NADPH. Phenolic hydroxyl group at the C-4 position in the coumarin skeleton is important for the maximal inhibition. Sequence of potency for the inhibitors in descending order: dicoumarol, 4-hydroxycoumarin, warfarin, coumarin
additional information
-
inhibition studies suggest that an essential disulfide-bridge is present at the binding site of zeta-crystallin
-
additional information
-
the results of the inhibition studies suggest that an essential Lys is located in the vicinity of the NADPH binding site
-
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
additional information
additional information
-
stopped-flow and laser-flash photolysis kinetic analyses, steady-state kinetics
-
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.5
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
4.5 - 10
-
pH 4.5: about 60% of maximal activity, pH 10: about 50% of maximal activity
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
25
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TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
-
the enzyme is expressed throughout the Trypanosoma cruzi life cycle
the gene for QR1 is isolated from an expressed sequence tag collection derived from the epidermis of a diploid Triticum monococcum L. 24 h after inoculation with the powdery mildew fungus Blumeria graminis EO Speer f. sp. tritici Em. Marchal. TmQR1 is repressed while TmQR2 is induced in the epidermis during powdery mildew infection
-
the enzyme is expressed throughout the Trypanosoma cruzi life cycle
-
the enzyme is expressed throughout the Trypanosoma cruzi life cycle
-
the concentration of zeta crystallin for the cataract phenotype is approximately half that present in tissue from normal control animals
-
the concentration of zeta crystallin for the cataract phenotype is approximately half that present in tissue from normal control animals
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in animals homozygous for the cataract phenotype the normal zeta-crystallin polypeptide is absent from the lens
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in animals homozygous for the cataract phenotype the normal zeta-crystallin polypeptide is absent from the lens
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the concentration of zeta crystallin for the cataract phenotype is approximately half that present in tissue from normal control animals
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the concentration of zeta crystallin for the cataract phenotype is approximately half that present in tissue from normal control animals
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
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it is possible that Arabidopsis P1-ZCr functions as a quinone reductase in vivo. Possible substrate quinones are not abundant in the cytosol, but under severe stress the quinones might be liberated from the cell compartments where they are normally sequestered, as exemplified by the release of polyphenols from vacuoles and polyphenol oxidase from thylakoid lumen upon the disruption of cells. Quinone reduction would not lead to the radical chain reaction, because superoxide dismutase is ubiquitous in cells
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PDB
SCOP
CATH
ORGANISM
UNIPROT
Coxiella burnetii (strain RSA 493 / Nine Mile phase I)
Pseudomonas syringae pv. tomato (strain ATCC BAA-871 / DC3000)
Pseudomonas syringae pv. tomato (strain ATCC BAA-871 / DC3000)
Saccharomyces cerevisiae (strain ATCC 204508 / S288c)
Saccharomyces cerevisiae (strain ATCC 204508 / S288c)
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
35000
36000
140000
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
dimer
homotetramer
tetramer
dimer
-
PtoQOR forms as a homologous dimer, each monomer containing two domains
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystallographic structure of human zeta-crystallin is reported. Enzyme shows a tetrameric structure
-
crystal structures of zeta-crystallin-like quinone oxidoreductase and its complexes with NADPH determined at 2.4 and 2.01 A resolution
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native enzyme and its complex with NADPH at 2.3 A and 2.8 A resolution. QOR forms a homodimer in the crystal by interaction of the betaF-strands in domain II, forming a large beta-sheet that crosses the dimer interface. NADPH is located between the two domains in the QOR-NADPH complex. The disordered segment involved in the coenzyme binding of apo-QOR becomes ordered upon NADPH binding. The segment covers an NADPH-binding cleft and may serve as a lid. The 2'-phosphate group of the adenine of NADPH is surrounded by polar and positively charged residues in QOR, suggesting that QOR binds NADPH more readily than NADH. The putative substrate-binding site of QOR, is largely blocked by nearby residues
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
4°C, 1 week, complete inactivation of purified enzyme
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
the quinone oxidoreductase activity of purified his-tagged recombinant mouse zeta-crystallin is comparable to that of purified native guinea pig lens zeta-crystallin, and to that of recombinant guinea pig zeta-crystallin. The method permits production of substantial amounts of recombinant zeta-crystallin for conducting studies on the biological role of this protein
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
expression in Escherichia coli, expression of TmQR1 is lethal to the cells, it is not possible to purify enough protein for further analysis
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
induced in presence of 9,10-phenanthrenequinone and by oxidative stress
Q7A492
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
T53F
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Tyr53Phe mutant displays a large increase in Km values for all substrates and the cofactor, but mainly towards 3-buten-2-one and propenal with a 30fold increase. For 3-penten-2-one, 3-nonen-2-one, 2-hexenal and 4-hydroxy-2-hexenal mutant also shows a decrease in kcat
T59F
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Tyr59Phe mutant exhibits almost the same kinetic parameter values as the wild-type enzyme for 2-alkenals,while the Km is increased for 4-hydroxy-2-hexenal
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
medicine
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QAO does not possess a protective role in menadione-induced free radical production and DNA damage in human cancer cells. Under aerobic conditions, menadiol produced by QAR is readily oxidized to menadione by two 1-electron steps producing the semiquinone and the parent quinone with concomitant production of superoxide anion, which leads to generation of hydroxyl radicals
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LINKS TO OTHER DATABASES (specific for EC-Number 1.6.5.5)
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