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Enzyme Nomenclature
Information on EC 1.6.5.4 - monodehydroascorbate reductase (NADH)
Word Map on EC 1.6.5.4
- 1.6.5.4
-
innate
-
neutrophil
- peroxidase
-
antibacterial
- epithelial
- superoxide
- staphylococcus
- aureus
-
antifungal
- disulfide
- catalase
- mucosal
-
bactericidal
-
cysteine-rich
-
paneth
-
ascorbate-glutathione
- lysozyme
- mosquito
- tick
- hemolymph
- jasmonate
- crohn
-
cathelicidins
-
cecropins
-
microbicidal
- hemocytes
-
azurophilic
- scorpion
- aegypti
- botrytis
- aedes
- mussel
- anopheles
-
1.6.4.2
- cinerea
-
1.11.1.11
- oxysporum
-
raphanus
- alternaria
- galloprovincialis
- brassicicola
-
toll
- dermacentor
-
necrotrophic
- gambiae
- ixodes
- guaiacol
-
triple-stranded
-
immune-related
- parasitica
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The enzyme appears in viruses and cellular organisms
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EC NUMBER 
COMMENTARY 
1.6.5.4
-
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RECOMMENDED NAME
GeneOntology No.
monodehydroascorbate reductase (NADH)
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate
-
-
-
-
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate
ping pong mechanism
-
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate
ping pong mechanism
-
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate
ping-pong mechanism
-
NADH + H+ + 2 monodehydroascorbate = NAD+ + 2 ascorbate
PpMDHARs follow a ping-pong kinetic mechanism; PpMDHARs follow a ping-pong kinetic mechanism; PpMDHARs follow a ping-pong kinetic mechanism
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oxidation
-
-
-
-
redox reaction
-
-
-
-
reduction
-
-
-
-
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
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SYSTEMATIC NAME
IUBMB Comments
NADH:monodehydroascorbate oxidoreductase
-
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CAS REGISTRY NUMBER
COMMENTARY
9029-26-9
-
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
interspecific cross of Nicotiana lansdorfii x Nicotiana sanderae
SwissProt
-
-
-
in the parasitic plant the activity is ten times lower than in etiolated and green plants
-
-
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
evolution
malfunction
metabolism
physiological function
additional information
malfunction
insertional inactivation of the MDAR2 (At3g09940) gene and the dehydroascorbate reductase 5 (DHAR5, At1g19570) gene shows that they are crucial for maintaining the interaction between Piriformosporaindica and Arabidopsis in a mutualistic state, and under drought stress in particular
malfunction
-
transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leaves
malfunction
-
transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leaves
-
metabolism
-
the enzyme is involved in the ascorbate recycling pathway, overview
metabolism
-
the enzyme is involved in the ascorbate recycling pathway, overview
-
physiological function
-
MDARis a key enzyme in the ascorbate-glutathione cycle, MDAR is crucial for ascorbate regeneration and essential for maintaining the reduced pool of ascorbate
physiological function
overexpression of chloroplastic monodehydroascorbate reductase enhances tolerance to temperature and methyl viologen-mediated oxidative stresses. Overexpression of chloroplastic MDAR plays an important role in alleviating photoinhibition of photosystem I and II and enhancing the tolerance to various abiotic stresses by elevating ascorbate level
physiological function
-
MDAR-OX plants do not show better root growth than wild type plants after exposure to 0.4 mM aluminium for 2 weeks
physiological function
-
the enzyme is involved in maintaining the reactive oxygen species scavenging capability of plant cells, as regeneration of ascorbate from its primary oxidation product monodehydroascorbate, an essential process and obviously indispensable. With its ability to directly regenerate ascorbate, MDHAR probably plays an important role in the plant antioxidant system by maintaining the pool of ascorbate. Chloroplastic MDHAR plays an important role in alleviating photoinhibition of PSII by elevating ascorbate (AsA) level under salt- and PEG-induced osmotic stress
physiological function
-
the enzyme negatively regulates ascorbate levels in Solanum lycopersicum, isozyme MDHAR3 activity has a negative impact on ascorbate levels in both leaves and fruits
physiological function
-
the enzyme negatively regulates ascorbate levels in Solanum lycopersicum, isozyme MDHAR3 activity has a negative impact on ascorbate levels in both leaves and fruits
-
physiological function
-
the enzyme is involved in maintaining the reactive oxygen species scavenging capability of plant cells, as regeneration of ascorbate from its primary oxidation product monodehydroascorbate, an essential process and obviously indispensable. With its ability to directly regenerate ascorbate, MDHAR probably plays an important role in the plant antioxidant system by maintaining the pool of ascorbate. Chloroplastic MDHAR plays an important role in alleviating photoinhibition of PSII by elevating ascorbate (AsA) level under salt- and PEG-induced osmotic stress
-
additional information
-
overexpression of the enzyme in rice plants increases the plant's salt tolerance. The leaf segments from transgenic lines remain green while the leaf segments from the wild-type plants show severe bleaching at 150 mM NaCl. The salinity tolerance of these transgenic rice lines is enhanced at germination and seedling stages
additional information
-
overexpression of MDHAR enhanced tolerance to osmotic stress
additional information
-
overexpression of MDHAR enhanced tolerance to osmotic stress
-
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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
2 ferricyanide + NADH
2 ferrocyanide + NAD+ + H+
-
enzyme also shows diaphorase activity, i.e. ferricyanide reductase
-
-
?
CO2 + H2O
HCO3- + H+
bifunctional enzyme showing monodehydroascorbate reductase and carbonic anhydrase, EC 4.2.1.1, activities
-
-
?
ferricyanide + reduced 2,6-dichlorophenolindophenol
ferrocyanide + 2,6-dichlorophenolindophenol
-
enzyme also shows diaphorase activity, i.e. ferricyanide reductase
-
-
?
NAD(P)H + monodehydroascorbate
NAD(P)+ + ascorbate
-
reduction of the radical monodehydroascorbate, via FAD as intermediary electron acceptor, FAD reduction by NADH producing a charge-transfer complex
-
-
?
NADH + 2,6-dichlorophenol indophenol
NAD+ + ?
-
about 10% of the activity with monodehydroascorbate radical
-
-
?
NADH + H+ + 2 monodehydroascorbate
NAD+ + 2 ascorbate
-
-
-
-
?
NADH + H+ + 2 monodehydroascorbate
NAD+ + 2 ascorbate
-
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
enzyme is involved in the ascorbate-glutathione cycle together with EC 1.8.5.1, and EC 1.6.4.2
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the monodehydroascorbate radical reacts with the fully reduced form of the enzyme with a diffusion-controlled rate
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
key enzyme for maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme of the ascorbate-glutathione cycle
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme may constitute part of cellular mechanisms which protect against and repair oxidant injury to biomolecules
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
enzyme is responsible for maintaining ascorbate concentrations in nectar
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
key enzyme in maintaining reduced pools of ascorbate
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
Pterocladia sp.
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in part of the transplasmamembrane redox system
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme supports cholesterol side chain cleavage, the enzyme functions to provide cytoplasmic reducing equivalents to intramitochondrial cytochrome P-450SCC
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the only physiologically important system for the regeneration of ascorbate
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
involvement of semidehydroascorbate reductase in the oxidation of NADH by lipid peroxide in mitochondria and microsomes
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme sustains glyoxysomal NAD+ during beta-oxidation, the glyoxylate cycle and gluconeogenesis in the endosperm during germination
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme participates in the regeneration of ascorbate for scavenging toxic oxygen species in potato tuber mitochondria
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is an effective scavenger of the monodehydroascorbate radical
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADPH + H+ + 2 monodehydroascorbate
NADP+ + 2 ascorbate
-
-
-
-
?
NADPH + monodehydroascorbate
NADP+ + ascorbate
NADH is the preferred electron donor
-
-
?
additional information
?
-
-
enzyme is also capable of reducing phenoxyl radicals which are generated by horseradish peroxidase with H2O2
-
-
-
additional information
?
-
reaction scheme, the enzyme is involved in nectary production in floral organs, multiple molecular mechanism responsible for expression in the nectary gland
-
-
-
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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
CO2 + H2O
HCO3- + H+
Q84UV8
bifunctional enzyme showing monodehydroascorbate reductase and carbonic anhydrase, EC 4.2.1.1, activities
-
-
?
additional information
?
-
Q84UV8
reaction scheme, the enzyme is involved in nectary production in floral organs, multiple molecular mechanism responsible for expression in the nectary gland
-
-
-
NADH + H+ + 2 monodehydroascorbate
NAD+ + 2 ascorbate
-
-
-
-
?
NADH + H+ + 2 monodehydroascorbate
NAD+ + 2 ascorbate
-
-
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
Q93X74
enzyme is involved in the ascorbate-glutathione cycle together with EC 1.8.5.1, and EC 1.6.4.2
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
key enzyme for maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme of the ascorbate-glutathione cycle
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme may constitute part of cellular mechanisms which protect against and repair oxidant injury to biomolecules
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
Q84UV8
enzyme is responsible for maintaining ascorbate concentrations in nectar
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
key enzyme in maintaining reduced pools of ascorbate
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
Pterocladia sp.
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in part of the transplasmamembrane redox system
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme supports cholesterol side chain cleavage, the enzyme functions to provide cytoplasmic reducing equivalents to intramitochondrial cytochrome P-450SCC
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the only physiologically important system for the regeneration of ascorbate
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
involvement of semidehydroascorbate reductase in the oxidation of NADH by lipid peroxide in mitochondria and microsomes
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme sustains glyoxysomal NAD+ during beta-oxidation, the glyoxylate cycle and gluconeogenesis in the endosperm during germination
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
enzyme participates in the regeneration of ascorbate for scavenging toxic oxygen species in potato tuber mitochondria
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is an effective scavenger of the monodehydroascorbate radical
-
-
?
NADH + monodehydroascorbate
NAD+ + ascorbate
-
the enzyme is involved in maintaining the ascorbic acid system in the reduced state
-
-
?
NADPH + H+ + 2 monodehydroascorbate
NADP+ + 2 ascorbate
-
-
-
-
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
additional information
-
MDHAR catalyses the reduction of the MDHA to AsA, using NADH or NADPH as an electron donor
-
FAD
contains a single non-covalently bound FAD coenzyme molecule; contains a single non-covalently bound FAD coenzyme molecule; contains a single non-covalently bound FAD coenzyme molecule
NADH
-
-
NADH
NADH is the preferred electron donor; NADH is the preferred electron donor
NADPH
NADH is the preferred electron donor; NADH is the preferred electron donor
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Zn2+
coordinated by residues His122, His124, and His141
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
beta-chloromercuribenzoate
PpMDHAR1 is almost completely inactivated after a 20 min preincubation with 0.25 mM beta-chloromercuribenzoate. At 0.05 mM the enzyme retains 11% of the initial activity.
chloromercuribenzoate
at 0.05 mM PpMDHAR3 retains 80% of the initial activity; PpMDHAR2 is almost completely inactivated after a 20 min preincubation with 0.25 mM chloromercuribenzoate. At 0.05 mM the enzyme retains 14% of the initial activity. The C69A mutant is more resistant to the inhibitory effects of chloromercuribenzoate than the wild type PpMDHAR2 protein
thiol-modifiying reagents
-
inhibition at the step of FAD reduction by NADH producing a charge-transfer complex
-
Mersalyl
-
partially reversed by thiol-containing reagents, pyridine mucleotides protect, when added prior to the inhibitor
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.052
2,6-dichlorophenol indophenol
-
maltose-binding protein-monodehydroascorbate reductase fusion protein
0.00144
monodehydroascorbate
-
native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.0015
monodehydroascorbate
-
recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.00151
monodehydroascorbate
-
mutant enzyme C117S, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.00155
monodehydroascorbate
-
mutant enzyme C117A, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.0057
monodehydroascorbate
-
maltose-binding protein-monodehydroascorbate reductase fusion protein
0.0053
NADH
-
maltose-binding protein-monodehydroascorbate reductase fusion protein
0.00621
NADH
-
recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.0063
NADH
-
native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
0.05
NADH
-
reaction with semidehydro-D(-)-ascorbic acid and semidehydro-L(+)-ascorbic acid
0.0215
NADPH
-
maltose-binding protein-monodehydroascorbate reductase fusion protein
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
121.4
NADH
Solanum lycopersicum
-
recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
126.6
NADH
Solanum lycopersicum
-
native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
19270
NADH
Solanum lycopersicum
-
recombinant wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
8
20420
NADH
Solanum lycopersicum
-
native wild type enzyme, in 50 mM Tris-HCl (pH 7.5), at 25°C
8
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Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
5.5 - 9.5
-
pH 5.5: about 60% of maximal activity, pH 9.5: about 75% of maximal activity
7.6 - 8.7
85% or greater activity between pH 7.6 and pH 8.7; 85% or greater activity between pH 7.6 and pH 8.7; 85% or greater activity between pH 7.6 and pH 8.7
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TEMPERATURE OPTIMUM
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
different developmental stages, high expression level
additional information
MDHAR activity increases gradually and significantly as ripening progresses,with overripe fruits having the highest activity
-
the MDHAR enzyme is active in different stages of fruit ripening and shows increased activity in the introgression lines containing the wild-type (Solanum pennellii) allele, and responds to chilling injury in tomato along with the reduced/oxidized ascorbate ratio. Low temperature storage of different tomato introgression lines with all or part of the quantitative trait loci for ascorbic acid and with or without the wild MDHAR allele shows that enzyme activity explains 84% of the variation in the reduced ascorbic acid levels of tomato fruit following storage at 4 °C, compared with 38% at harvest under non-stress conditions. A role is indicated for MDHAR in the maintenance of ascorbate levels in fruit under stress conditions. An increased fruit MDHAR activity and a lower oxidation level of the fruit ascorbate pool are correlated with decreased loss of firmness because of chilling injury
additional information
-
leaf anti-oxidative system, antisense suppression of 2-cysteine peroxiredoxin does not enhances activity
additional information
detailed analysis of expression during nectary development in flower organs, overview
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
activity of the enzyme depends on the interaction of proteins and lipids and is therefore of necessity dependent upon the integrity of a certain micellar structure in the endoplasmic reticulum
additional information
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integrity of glucan moieties of the cell surface glycoconjugates are necessary for the optimal function of the enzyme activity; plasma membrane
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outer mitochondrial membrane, highest activity in the cis-Golgi membrane fraction
additional information
isoforms with different subcellular localization
-
additional information
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MDHAR isoforms in both the cytosol and peroxisome
-
additional information
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MDHAR isoforms in both the cytosol and peroxisome
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
28536
x * 40000, SDS-PAGE, x * 28536, amino acid sequence calculation
40000
47000
50000
53000
54000
40000
x * 40000, SDS-PAGE, x * 28536, amino acid sequence calculation
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SUBUNITS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
monomer
?
x * 40000, SDS-PAGE, x * 28536, amino acid sequence calculation
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Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purified recombinant enzyme, immediately after purification by hanging drop vapour diffusion method, 0.005 ml of protein solution containing 10 mg/ml protein, mixed with equal volume of reservoir solution containing 20-25% PEG 6000, 0.1 M CaCl2, 50 mM Tris-HCl, pH 8.0, equilibration against 1 ml reservoir solution, 20°C, 1 week, cryoprotection by 30% glycerol, X-ray diffraction structure determination and analysis at 2.4 A resolution
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pH STABILITY
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
35 - 62
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the activity of wild type MDAR has no much change after heat treatment at temperatures below 35°C, steep decrease of activity is observed between 35 and 55°C, and a complete loss in activity occurs above 62°C. The midpoint of thermal inactivation of wild type MDAR is about 52.1°C
60
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
4°C, maltose-binding protein-monodehydroascorbate reductase fusion protein, in presence of 2-mercaptoethanol, 1 month, stable
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STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-20°C, 10 mM Tris/HCl buffer, pH 7.4, 2 mM dithiothreitol, 25% glycerol, 1 month, stable
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-80°C, buffer containing 10 mM potassium phosphate at pH 6.5 10 mM 2-mercaptoethanol and 0.1 mM EDTA, several months, no loss of activity
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4°C, 4°C, in absence of dithiothreitol, complete loss of activity within 1 day
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4°C, pH 8, 30 d, almost complete loss of activity, residual activity up to 38% when stored in presence of 1-10 mM MgSO4
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Butyl-Toyopearl column chromatography, HiTrap Q column chromatography and Blue Sepharose 6FF column chromatography
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Phenyl Superose gel filtration, Blue Sepharose column chromatography and DEAE cellulose column chromatography
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several native enzyme forms from lens soluble fraction by gel filtration, affinity chromatography, native isoelectric focusing, and 2D-electrophoresis, about 1400fold
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis
DNA and amino acid sequence determination and analysis, construction of a cDNA library, expression in Escherichia coli
expressed in Escherichia coli
expressed in Escherichia coli BL21(DE3) cells and in Nicotiana tabacum cv. petit havana
expressed in Nicotiana tabacum; overexpression in Nicotiana tabacum. The transgenic plants exhibit up to 2.1fold higher monodehydroascorbate reductase activity and 2.2fold higher level of reduced ascorbate compared to non-transformed control plants. The transgenic plants show enhanced stress tolerance in term of significantly higher net photosynthesis rates under ozone, salt and polyethylene glycol stresses and greater PSII effective quantum yield under ozone and salt stresses
expression in Escherichia coli; expression in Escherichia coli; expression in Escherichia coli
expression of mitochondrial and chloroplastic isozymes as GFP-fusion proteins in transgenic Arabidopsis plants, targeting of recombinant fusion proteins to the organelles in vivo in transgenic plants, dual targeting is achieved by multiple transcription initiation sites, 2 transcripts, a small and a large one, both have an N-terminal extension
gene MDHAR3, functional overexpression in transgenic Solanum lycopersicum plant leaves, quantitative reverse-transcriptase PCR expression analysis
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high level expression in Escherichia coli, using the T7 RNA polymerase expression system
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quantitative reverse-transcription PCR expression analysis, functional recombinant enzyme overexpression driven by a CaMV double 35S promoter in Oryza sativa in three stable transgenic lines, MT22, MT24 and MT25 as single or multiple copy gene, using the Agrobacterium tumefaciens strain LBA4404 transfection method. All transgenic lines show better yield attributes such as a higher tiller number and increased 1000-grain weight compared to non-transgenics. They also show tolerance to salt at germination and seedling stages
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
ascorbate, the MDAR2 (At3g09940) and the dehydroascorbate reductase 5 (DHAR5, At1g19570) mRNA levels are upregulated in Arabidopsis roots colonized by the beneficial endophytic fungus Piriformosporaindica
MDHAR transcripts and enzyme activities are significantly up-regulated in the leaves of acerola under cold (4°C for 24 h) and salt (treatment with 150 mM NaCl over 9 days) stress conditions. MDHAR activity increases gradually and significantly as ripening progresses,with overripe fruits having the highest activity
the MDHAR expression level is decreased firstly and then increased, the maximum level is observed after treatment for 12 h with 200 mM NaCl or 20% PEG6000, overview. The stressful treatment accelerates degradation of mRNA at the early stage, then with the duration of treatment the plants respond to the stress and the synthesis of MDHAR increases to protect the plant from stressful damage
the MDHAR expression level is decreased firstly and then increased, the maximum level is observed after treatment for 12 h with 200 mM NaCl or 20% PEG6000, overview. The stressful treatment accelerates degradation of mRNA at the early stage, then with the duration of treatment the plants respond to the stress and the synthesis of MDHAR increases to protect the plant from stressful damage
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the MDHAR expression level is decreased firstly and then increased, the maximum level is observed after treatment for 12 h with 200 mM NaCl or 20% PEG6000, overview. The stressful treatment accelerates degradation of mRNA at the early stage, then with the duration of treatment the plants respond to the stress and the synthesis of MDHAR increases to protect the plant from stressful damage
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C69A
mutation has a negligible effect on enzyme activity under standard reaction conditions. The C69A mutant is more resistant to the inhibitory effects of beta-chloromercuribenzoate than the wild type PpMDHAR2 protein
C117A
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the binding affinity of NADH in the mutant MDAR is lower than that of wild type MDAR as indicated by about 1.5-3fold increase of the Km value for NADH, the mutant is less thermo-stable than the wild type enzyme
C117S
-
the binding affinity of NADH in the mutant MDAR is lower than that of wild type MDAR as indicated by about 1.5-3fold increase of the Km value for NADH, the mutant is less thermo-stable than the wild type enzyme
additional information
additional information
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overexpression of MDHAR enhanced tolerance to osmotic stress
additional information
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transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leave. In all three lines where MDHAR3 is silenced (MDS lines), a significant decrease in overall MDHAR activity is observed in leavess. Transcript levels of MDHAR1 (SGN-U584073) and MDHAR2 (SGN-U583672) remain unaffected by modification of MDHAR3
additional information
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transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leave. In all three lines where MDHAR3 is silenced (MDS lines), a significant decrease in overall MDHAR activity is observed in leavess. Transcript levels of MDHAR1 (SGN-U584073) and MDHAR2 (SGN-U583672) remain unaffected by modification of MDHAR3
-
additional information
-
overexpression of MDHAR enhanced tolerance to osmotic stress
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Renatured/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
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LINKS TO OTHER DATABASES (specific for EC-Number 1.6.5.4)
Information
