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Information on EC 1.11.1.11 - L-ascorbate peroxidase
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1.11.1.11 L-ascorbate peroxidaseIUBMB Comments
A heme protein. Oxidizes ascorbate and low molecular weight aromatic substrates. The monodehydroascorbate radical produced is either directly reduced back to ascorbate by EC 1.6.5.4 [monodehydroascorbate reductase (NADH)] or undergoes non-enzymic disproportionation to ascorbate and dehydroascorbate.
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Word Map
- 1.11.1.11
- catalase
- seedling
- malondialdehyde
- chlorophyll
- guaiacol
- dehydroascorbate
- shoot
- chloroplast
- monodehydroascorbate
-
drought
- gsh
- cultivar
-
non-enzymatic
-
carotenoid
- cadmium
-
hydroponic
- peroxidases
-
electrolyte
-
foliar
- thylakoidal
- triticum
-
chilling
- aestivum
-
phytotoxicity
- photosystem
-
1.6.4.2
- mdhar
- lipoxygenase
-
abscisic
-
ascorbate-glutathione
- analysis
- agriculture
-
transpiration
-
salt-stressed
- juncea
-
ros-scavenging
-
salt-tolerant
-
postharvest
-
phytoremediation
-
photoinhibition
-
arbuscular
- phytochelatins
-
hoagland
-
cd-induced
-
cptio
- violaxanthin
- synthesis
-
ultraviolet-b
-
phytoextraction
- fe-sods
-
aba-induced
-
xanthophyl
-
non-photochemical
The enzyme appears in viruses and cellular organisms
Reaction Schemes
2
+
+
2
=
+
+
2
Synonyms
Am-pAPX1, APEX2, APOX, APX, APX 1, APX 2, APX1, APX2, APX3, APX4, 
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
APX
APX1
APX2
APX6
ascorbate peroxidase
ascorbate peroxidase 1
ascorbate peroxidase 2
ascorbate peroxidase 3
ascorbate peroxidase 4
ascorbate peroxidase 5
ascorbate peroxidase 6
ascorbate peroxidase 7
ascorbate peroxidase 8
ascorbic acid peroxidase
-
-
-
-
L-ascorbic acid peroxidase
-
-
-
-
L-ascorbic acid-specific peroxidase
-
-
-
-
LmAPX
OsAPx8
peroxidase, ascorbate
-
-
-
-
stromal ascorbate peroxidase
ascorbate peroxidase
-
-
-
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2 L-ascorbate + H2O2 + 2 H+ = L-ascorbate + L-dehydroascorbate + 2 H2O
overall reaction
-
-
-
2 monodehydroascorbate = L-ascorbate + L-dehydroascorbate
spontaneous
-
-
-
2 L-ascorbate + H2O2 + 2 H+ = 2 monodehydroascorbate + 2 H2O
(1a)
-
-
-
2 L-ascorbate + H2O2 + 2 H+ = 2 monodehydroascorbate + 2 H2O
mechanism involves accumulation of a transient enzyme intermediate
-
2 L-ascorbate + H2O2 + 2 H+ = 2 monodehydroascorbate + 2 H2O
mechanism, structural hints to instability during catalysis
-
2 L-ascorbate + H2O2 + 2 H+ = 2 monodehydroascorbate + 2 H2O
mechanism; mechanism for electron transfer
Q43758
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oxidation
peroxidation
-
-
-
-
redox reaction
-
-
-
-
reduction
oxidation
-
-
-
-
reduction
-
-
-
-
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PATHWAY SOURCE
PATHWAYS
BRENDA
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SYSTEMATIC NAME
IUBMB Comments
L-ascorbate:hydrogen-peroxide oxidoreductase
A heme protein. Oxidizes ascorbate and low molecular weight aromatic substrates. The monodehydroascorbate radical produced is either directly reduced back to ascorbate by EC 1.6.5.4 [monodehydroascorbate reductase (NADH)] or undergoes non-enzymic disproportionation to ascorbate and dehydroascorbate.
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CAS REGISTRY NUMBER
COMMENTARY
72906-87-7
-
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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
2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) + H2O2 + H+
? + H2O
-
-
-
-
?
2,2'-azino-di-(3-ethyl-benzothiazoline-(6)-sulfonic acid) + H2O2
? + H2O
-
3% relative activity to L-ascorbate
-
?
2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) + H2O2
?
-
cytosolic ascorbate peroxidase shows 3% activity compared to L-ascorbate, in the presence of 0.1 mM H2O2 and 3.6% activity compared to L-ascorbate in the presence of 0.5 mM H2O2
-
-
?
cysteine + H2O2
? + H2O
-
enzyme partially purified from whole body homogenate, 40% of the activity with L-ascorbate
-
?
cytochrome c + H2O2
?
-
able to use both ascorbate and cytochrome c as reducing electron donors
-
-
?
D-araboascorbic acid + H2O2
dehydroascorbate + H2O
-
56% activity relative to L-ascorbate
-
?
D-iso-ascorbate + H2O2
dehydroascorbate + H2O
Chlamydomonas sp.
native enzyme: the activity with D-isoascorbate corresponds to 131% of that found with ascorbate, recombinant enzyme: the activity with D-isoascorbate corresponds to 129% of that found with ascorbate
-
?
ferrocyanide + H2O2
ferricyanide + H2O
-
the Cys32Ser mutation has little effect on the kinetics of ferrocyanide turnover, but the DTNB modification decreases activity by approximately 90% at 300 mM ferrocyanide
-
?
L-ascorbate + tert-butyl hydroperoxide
?
-
17.4% activity compared to H2O2
-
-
?
NADH + H+ + H2O2
NAD+ + H2O
-
10% of the activity with ascorbate, APX 1, 1% of the activity with ascorbate, APX 2
-
-
?
NADPH + H+ + H2O2
NADP+ + H2O
-
27% of the activity with ascorbate, APX 1, 21% of the activity with ascorbate, APX 2
-
-
?
p-cresol + cumene-hydroperoxide
4a,9b-dihydro-8,9b-dimethyl-3(4H)-dibenzofuranone + 2,2'-dihydroxy-5,5'-dimethylbiphenyl + 1,1-dimethylbenzylalcohol + bis-(1-methyl-1-phenylethyl)peroxide
-
-
the formation of bis-(1-methyl-1-phenylethyl)peroxide derives from the reaction of 1,1-dimethylbenzylalcohol with either p-cresol or 2,2'-dihydroxy-5,5'-dimethylbiphenyl
?
p-cresol + H2O2
4a,9b-dihydro-8,9b-dimethyl-3(4H)-dibenzofuranone + 2,2'-dihydroxy-5,5'-dimethylbiphenyl + H2O
-
-
these products, which are derived from reactions of the p-methylphenoxy radical, itself form as a direct result of single-electron oxidation of p-cresol by the enzyme, can be accommodated from the known chemistry of the radical products, the product ratio 4alpha,9beta-dihydro-8,9beta-dimethyl-3(4H)-dibenzofuranone: 2,2'-dihydroxy-5,5'-dimethylbiphenyl is found to depend on enzyme concentration
?
pyrocatechol + H2O2
1,2-benzoquinone + H2O
-
low activity compared to L-ascorbate
-
?
reductic acid + H2O2
?
-
i.e. 2,3-dihydroxy-2-cyclopenten-1-one, 7.1% activity relative to L-ascorbate
-
?
2 L-ascorbate + H2O2 + 2 H+
L-ascorbate + L-dehydroascorbate + 2 H2O
-
-
-
?
2 L-ascorbate + H2O2 + 2 H+
L-ascorbate + L-dehydroascorbate + 2 H2O
U5RZT9
-
-
-
?
2,2'-azino-di-[3-ethylbenzothiazoline-(6)-sulfonic acid] + H2O2
?
-
-
-
-
?
2,2'-azino-di-[3-ethylbenzothiazoline-(6)-sulfonic acid] + H2O2
?
-
-
-
-
?
cytochrome c + H2O2
? + H2O
-
enzyme partially purified from whole body homogenate, 44% of the activity with L-ascorbate
-
?
glutathione + H2O2
? + H2O
-
enzyme partially purified from whole body homogenate: 22% of the activity with L-ascorbate, enzyme partially purified from regurgitant: 0% relative activity to L-ascorbate, when assayed at the same concentration
-
?
glutathione + H2O2
? + H2O
-
30% of the activity with ascorbate, APX 1, 13% of the activity with ascorbate, APX 2
-
-
?
guaiacol + H2O2
?
Chlamydomonas sp.
native enzyme: the activity corresponds to 7.2% of that found with L-ascorbate, recombinant enzyme: the activity corresponds to 8% of that found with L-ascorbate
-
?
guaiacol + H2O2
?
-
the reaction rate is approximately equal to the rate with L-ascorbate
-
?
guaiacol + H2O2
?
-
recombinant enzyme 1: 6% activity relative to L-ascorbate, recombinant enzyme 2: 11% relative activity to L-ascorbate
-
?
guaiacol + H2O2
?
-
cytosolic ascorbate peroxidase shows 12% activity compared to L-ascorbate, in the presence of 0.1 mM H2O2 and 24.7% activity compared to L-ascorbate in the presence of 0.5 mM H2O2
-
-
?
guaiacol + H2O2
?
-
form C enzyme, only onesixteenth the rate observed with L-ascorbate
-
?
guaiacol + H2O2
? + H2O
-
45% of the activity with ascorbate, APX 1, 15% of the activity with ascorbate, APX 2
-
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme works for protection of cell membrane, by reducing the peroxide compounds generated endogenously from unsaturated fatty acids
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme appears to be the sole agent destroying H2O2
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme is responsible for most H2O2 removal outside of peroxisomes in root nodules
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme may be important in removing H2O2 and lipid peroxides in insects
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
role of the mitochondrial enzyme in the scanvenging of toxic oxygen species inside potato tuber mitochondria
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
L-ascorbate is the most effective natural electron donor
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
Chlamydomonas sp.
native and recombinant enzyme, no activation is observed, when the enzyme is incubated with H2O2 under anaerobic conditions, thus one of the reasons for the stability mechanism in the enzyme may be the insusceptibility of compound I to H2O2
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
tert-butyl hydroperoxide and cumene hydroperoxide also serve as electron acceptor
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
tert-butyl hydroperoxide and cumene hydroperoxide also serve as electron acceptor
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
L-ascorbate is the most effective natural electron donor
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
cytosolic ascorbate peroxidase shows 100% activity in the presence of 0.1 mM and 0.5 mM H2O2
-
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
the DTNB-modified enzyme exhibits only 1.3% wild-type activity when ascorbate is used as substrate, the DTNB-modified enzyme reacts normally with peroxide to give compound I but the rates of reduction of both compounds I and II by ascorbate are dramatically slowed. The Cys32Ser mutant has one-third wild-type activity. The ascorbate interactions with the enzyme are partly mediated through electrostatic interactions
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
an equimolar mixture of native enzyme and H2O2 forms some transient compound I which, within 60 s is converted to compound II, addition of 5 mM ascorbate rapidly reduces compound II back to the native enzyme
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
highly specific for L-ascorbate
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
-
-
-
?
L-ascorbic acid + cumene hydroperoxide
dehydroascorbate + 1,1-dimethylbenzylalcohol + H2O
Chlamydomonas sp.
no activity
-
-
-
L-ascorbic acid + cumene hydroperoxide
dehydroascorbate + 1,1-dimethylbenzylalcohol + H2O
-
no activity
-
-
-
L-ascorbic acid + cumene hydroperoxide
dehydroascorbate + 1,1-dimethylbenzylalcohol + H2O
-
-
-
?
L-ascorbic acid + cumene hydroperoxide
dehydroascorbate + 1,1-dimethylbenzylalcohol + H2O
-
34% of the activity with H2O2
-
?
L-ascorbic acid + tert-butylhydroperoxide
dehydroascorbate + tert-butylalcohol
Chlamydomonas sp.
no activity
-
-
-
L-ascorbic acid + tert-butylhydroperoxide
dehydroascorbate + tert-butylalcohol
-
no activity
-
-
-
L-ascorbic acid + tert-butylhydroperoxide
dehydroascorbate + tert-butylalcohol
-
-
-
?
L-ascorbic acid + tert-butylhydroperoxide
dehydroascorbate + tert-butylalcohol
-
both enzymes A and B
-
?
L-ascorbic acid + tert-butylhydroperoxide
dehydroascorbate + tert-butylalcohol
-
92% of the activity with H2O2
-
?
NADPH + H2O2
? + H2O
-
enzyme partially purified from whole body homogenate: 93% of the activity with L-ascorbate, enzyme partially purified from regurgitant: 36% of the activity with L-ascorbate, when assayed at the same concentration
-
?
o-dianisidine + H2O2
?
-
reaction rate approximately equal to the rate with L-ascorbate
-
?
o-dianisidine + H2O2
?
-
the oxidation rate is only 8.6% of that with L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
2.5-fold higher rate than that of L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
Chlamydomonas sp.
native enzyme: the activity corresponds to 121% of that found with L-ascorbate, recombinant enzyme: the activity corresponds to 130% of that found with L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
62.6% activity relative to L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
73.1% activity relative to L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
the reaction rate is 38-fold higher than the rate with L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
recombinant enzyme 1: 355% activity relative to L-ascorbate, recombinant enzyme 2: 304% activity relative to L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
723% activity relative to L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
the DTNB-modified enzyme exhibits full activity
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
the oxidation rate is only 5.5% of that with L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
the activity is lower than with L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
low activity compared to L-ascorbate
-
?
pyrogallol + H2O2
3-hydroxybenzo-1,2-quinone + H2O
-
238% activity relative to L-ascorbate
-
-
?
pyrogallol + H2O2
?
-
cytosolic ascorbate peroxidase shows 29% activity compared to L-ascorbate, in the presence of 0.1 mM H2O2 and 208% activity compared to L-ascorbate in the presence of 0.5 mM H2O2
-
-
?
additional information
?
-
-
the cytosolic enzyme exhibits no activity with: glutathione, cytochrome c and NAD(P)H
-
-
-
additional information
?
-
Chlamydomonas sp.
native and recombinant enzyme, no activity with: glutathione, NADPH and cytochrome c
-
-
-
additional information
?
-
-
no activity with: glutathione, cytochrome c, NADH and NADPH
-
-
-
additional information
?
-
-
the activity with glutathione is less than 1.1% of that with L-ascorbic acid, no activity with: cytochrome c, NADH, NADPH, palmitic acid and triose reductone
-
-
-
additional information
?
-
-
no activity with: NADH, NADPH, cytochrome c, glutathione and palmitic acid as the natural electron donor
-
-
-
additional information
?
-
-
no activity with: NAD(P)H, reduced glutathione or urate
-
-
-
additional information
?
-
A7KIX5
GhAPX1 is involved in hydrogen peroxide homeostasis during cotton fibre development
-
-
-
additional information
?
-
-
GhAPX1 is involved in hydrogen peroxide homeostasis during cotton fibre development
-
-
-
additional information
?
-
-
cytosolic and chloroplastic ascorbate peroxidase shows no activity with tert-butyl hydroperoxide and cumene hydroperoxide, pyrocatechol, hydroxyurea, GSH, cytochrome c, NADH, and NADPH. Chlorplastic ascorbate peroxidase displays no activity with pyrogallol, guaiacol, pyrocatechol, and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)
-
-
-
additional information
?
-
-
guaiacol and pyrogallol are substrates, but the enzyme is inactivated by the oxidized guaiacol and pyrogallol products
-
-
-
additional information
?
-
-
experimental and modelled enantiomeric ratios R: S for oxidation of thioethers by recombinant enzyme and mutant Trp-41-Ala
-
-
-
additional information
?
-
-
no activity with: cytochrome c, reduced glutathione, NADH, NADPH, 6-palmityl-ascorbate, ascorbate-2-sulfate, guaiacol, 3,3'-diaminobenzidine, pyrocatechol or D-iso-ascorbate
-
-
-
additional information
?
-
-
can cooperate with monodehydroascorbate reductase in glyoxysomal membrane to oxidize NADH, regenerate ascorbate, detoxify H2O2
-
-
-
additional information
?
-
-
reaction includes formation of a compound I-like product, characteristic of the generation of a tryptophanyl radical-cation at residue W233. In addition, formation of a C222-derived radical is observed. electron transfer between Trp233 and Cys222 is possible and likely to participate in the catalytic cycle
-
-
-
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NATURAL SUBSTRATE
NATURAL 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
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme works for protection of cell membrane, by reducing the peroxide compounds generated endogenously from unsaturated fatty acids
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme appears to be the sole agent destroying H2O2
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme is responsible for most H2O2 removal outside of peroxisomes in root nodules
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
the enzyme may be important in removing H2O2 and lipid peroxides in insects
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
physiological role of the enzyme: removal of H2O2, prevention of H2O2 accumulation
-
?
L-ascorbate + H2O2
dehydroascorbate + 2 H2O
-
role of the mitochondrial enzyme in the scanvenging of toxic oxygen species inside potato tuber mitochondria
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
A7KIX5, C6ZDA9, C6ZDB0, Q39780
-
-
-
?
L-ascorbate + H2O2
dehydroascorbate + H2O
Q09Y74, Q09Y76, Q09Y77, Q09Y78, Q3I5C3, Q3I5C4, Q3SC88
-
-
-
?
additional information
?
-
A7KIX5
GhAPX1 is involved in hydrogen peroxide homeostasis during cotton fibre development
-
-
-
additional information
?
-
-
GhAPX1 is involved in hydrogen peroxide homeostasis during cotton fibre development
-
-
-
additional information
?
-
-
can cooperate with monodehydroascorbate reductase in glyoxysomal membrane to oxidize NADH, regenerate ascorbate, detoxify H2O2
-
-
-
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
heme
-
covalent linking of Trp41 to the heme group in ascorbate peroxidase can occur on exposure of the enzyme to peroxide. A reaction mechanism involving formation of a protein radical at Trp41 is implicated to account for this observation
heme
-
determination of the redox potential for the Fe3+/Fe2+, CI/Fe3+, CI/II, and CII/Fe3+ redox couples in rsAPX and various site-directed variants by direct potentiometric titration
additional information
-
electronic, EPR, and NMR spectra are consistent with a high-spin ferric resting state for the enzyme at 298K, low temperature EPR and electronic absorption experiments indicate formation of a low-spin heme derivative at these temperatures, the midpoint reduction potential for the Fe(III)/Fe(II) redox couple, determined by spectroelectrochemistry is -159 mV vs SHE, sodium phosphate: pH 7, 25°C, 0.10 M
-
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Fe
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
2,2,6,6-tetramethylpiperidinyl-1-oxide
-
formation of 2,2,6,6-tetramethylpiperidinyl-1-oxy-adducts and subsequent oxidation of the cysteine residue located near the propionate group of heme leads to loss of enzyme activity
2,2,6,6-tetramethylpiperidinyl-1-oxyl radical
-
formation of 2,2,6,6-tetramethylpiperidinyl-1-oxy-adducts and subsequent oxidation of the cysteine residue located near the propionate group of heme leads to loss of enzyme activity
2,6-dichloroisonicotinic acid
-
54% inhibition at 0.1 mM, 95% inhibition at 1 mM, the inhibition is not time-dependent
3,3'-dithiobis(6-nitrobenzoic acid)
-
5 mM, 80% residual activity, APX 1, 24% residual activity, APX 2
imidazole
J7EIR8
enzyme shows a decrease in its activity with increasing imidazole concentration, approximately 50% activity is lost in the presence of 0.8 M imidazole
p-chloromercuriphenyl sulfonic acid
-
100% inhibition at 0.05 mM, recombinant enzyme 1 and 2
p-hydroxymercuribenzoate
-
43% inhibition at 0.005 mM, 100% inhibition at 0.05 mM
2-mercaptoethanol
-
enzyme form C: 50% inhibition at 5 mM, 6 min, 100% inhibition after 18 min
C2H2
-
recombinant enzyme 1: 94% inhibition at 0.1 ml per l, recombinant enzyme 2: 2% inhibition at 0.1 ml per l
dithiothreitol
-
enzyme form C: 100% inhibition at 0.1 mM for 5 min, 57% of the inhibition can be recovered by filtration on Sephadex G-25 and a further 14% is recovered after the addition of homocystine at 2 mM
EDTA
-
slight inhibition, but when the enzyme is incubated with EDTA 1 mM at 37°C for 3 min in the absence of sucrose and ferrous sulfate there is nearly complete inhibition
H2O2
wild-type enzyme has a half-time of inactivation of less than 10 sec. Triple mutant C26S/W35F/C126A retains 50% of the initial activity after H2O2 treatment for 3 min
H2O2
-
when inactivated by H2O2, heme is irreversibly cross-linked to the APX apoprotein. tsAPXW35F is inactivated in 3 min by H2O2. It is possible that tsAPXW35F is inactivated by adistinct mechanism because the heme can no longer be cross-linked to the enzyme
hydroxylamine
-
recombinant enzyme 1: 74% inhibition at 1 mM and 100% inhibition at 10 mM, recombinant enzyme 2: 86% inhibition at 1 mM and 100% inhibition at 10 mM
KCN
-
recombinant enzyme 1: 69% inhibition at 0.1 mM and 100% inhibition at 0.5 mM, recombinant enzyme 2: 81% inhibition at 0.1 mM and 100% inhibition at 0.5 mM
p-chloromercuribenzoate
-
87% inhibition at 0.005 mM, inactivation is partially reversible, 2-mercaptoethanol protects
salicylic acid
-
biologically active, reversible inhibition, 59% inhibition at 0.1 mM, 83% inhibition at 0.2 mM, 95% inhibition at 1 mM, the inhibition is not time-dependent
Zn2+
-
leaves of plants grown with both low and high Zn show accumulation of lipid peroxides, ascorbate and dehydroascorbate, associated with a decrease in the activity of the enzyme
additional information
-
not inhibitory up to 100 mM: cyanide, azide, aminotriazole
-
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
methyl jasmonate
-
knockout mutant plants lacking Apx1 show high sensitivity to wounding and methyl jasmonate treatment. In the leaves of wild-type plants, H2O2 accumulates only in the vicinity of the wound, while in the leaves of the knockout mutant plants it accumulates extensively from damaged to undamaged regions. During methyl jasmonate treatment, the levels of H2O2 are much higher in the leaves of Apx1 knockout plants
nitric oxide
-
causes an increase in the total enzymatic activity of ascorbate peroxidase. The nitric oxide-induced changes in ascorbate peroxidase enzymatic activity are coupled to altered nodule H2O2 content. Enzymatic activity of the largest isoform, Apx1 is upregulated by 11% in response to 5 microM of nitric oxide donor DETA/NO and 21% in response to 10 microM DETA/NO. 5 microM of DETA/NO increase the enzymatic activity of the second largest isoform Apx2 by about 57%. Treatment of nodulated soybean with 5 microM DETA/NO upregulates the smallest nodule isoform Apx3 enzymatic activity by 228% compared to untreated controls
phenanthrene
-
exposure to 0.5 microM phenanthrene results in significant increase in the levels of both enzymatic and non-enzymatic antioxidants, with the levels of total glutathione and ascorbate doubling, the activitiy of APOX increasing by 2fold after 72 h of exposure to phenanthrene
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.000043
2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)
-
pH 7.0, temperature not specified in the publication. Hill coefficient n is 1.0
0.493
L-ascorbate
-
recombinant full length enzyme, in 50 mM potassium phosphate buffer, pH 7.0, at 22°C
0.5
L-ascorbate
U5RZT9
pH 7.0, temperature not specified in the publication
0.804
L-ascorbate
-
pH 7.0, temperature not specified in the publication. Non-Michaelis-Menten kinetics, Hill ccoefficient n is 1.6
additional information
additional information
-
the reaction does not follow Michaelis-Menten kinetics, Hill plots
-
additional information
additional information
-
both forms of the enzyme show a very high affinity for H2O2, Km values below 0.005
-
additional information
additional information
-
Km values comparable with those of higher plants
-
additional information
additional information
-
ascorbate can saturate the ascorbate-dependent hemoperoxidase activity indicating that the enzyme obeys Michaelis-Menten kinetics
-
additional information
additional information
-
Km of recombinant enzyme-B produced in E. coli
-
additional information
additional information
-
untreated cells, sigmoidal dependence of reaction rate on ascorbate concentration, in heat shock cells, hyperbolic dependence of reaction rate on ascorbate concentration and 5-fold decrease in Km-value
-
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.4
2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)
-
pH 7.0, temperature not specified in the publication. Hill coefficient n is 1.0
577
H2O2
-
recombinant full length enzyme, in 50 mM potassium phosphate buffer, pH 7.0, at 22°C
49.6
L-ascorbate
U5RZT9
pH 7.0, temperature not specified in the publication
161
L-ascorbate
-
pH 7.0, temperature not specified in the publication. Non-Michaelis-Menten kinetics, Hill ccoefficient n is 1.6
754
L-ascorbate
-
recombinant full length enzyme, in 50 mM potassium phosphate buffer, pH 7.0, at 22°C
additional information
additional information
-
substrate: guaiacol, effects of Cys32Ser mutagenesis and DTNB-modification
-
additional information
additional information
-
of recombinant enzyme-B produced in E. coli
-
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
16500
H2O2
-
recombinant full length enzyme, in 50 mM potassium phosphate buffer, pH 7.0, at 22°C
14.5
L-ascorbate
U5RZT9
pH 7.0, temperature not specified in the publication
1530
L-ascorbate
-
recombinant full length enzyme, in 50 mM potassium phosphate buffer, pH 7.0, at 22°C
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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
0.01
-
crude extract of root nodules, the activity is rapidly lost after extraction
0.26
-
effect of abscisic acid and EGTA on APX activity, 1 day following chilling stress
0.27
-
effect of abscisic acid and EGTA on APX activity, 7 days, under normal temperature
0.28
-
effect of abscisic acid and EGTA on APX activity, 4 days following chilling stress; effect of abscisic acid and LaCl3 on APX activity, 4 days following chilling stress
0.3
-
effect of EGTA on APX activity, 4 days following chilling stress; in water, 4 days following chilling stress
0.31
-
effect of abscisic acid and EGTA on APX activity, 4 days, under normal temperature; effect of abscisic acid on APX activity, 7 days, under normal temperature; effect of LaCl3 on APX activity, 7 days, under normal temperature
0.32
-
effect of abscisic acid and LaCl3 on APX activity, 1 day following chilling stress; effect of EGTA on APX activity, 1 day following chilling stress; effect of LaCl3 on APX activity, 4 days following chilling stress; in water, 1 day following chilling stress
0.33
-
effect of abscisic acid and LaCl3 on APX activity, 4 days, under normal temperature; effect of abscisic acid and LaCl3 on APX activity, 7 days, under normal temperature; effect of EGTA on APX activity, 4 days, under normal temperature; effect of EGTA on APX activity, 7 days, under normal temperature; in water, 7 days, under normal temperature
0.36
-
effect of abscisic acid on APX activity, 4 days following chilling stress; effect of LaCl3 on APX activity, 1 day following chilling stress
0.37
-
effect of LaCl3 on APX activity, 4 days, under normal temperature
0.4
-
effect of abscisic acid on APX activity, 1 day following chilling stress
0.45
-
effect of abscisic acid on APX activity, 4 days, under normal temperature
4.32
-
crude extract of root nodules, activity is only detected when soluble polyvinylpolypyrrolidone is included in the buffer and O2 is excluded by through degassing of buffers and performing all extraction steps under a vigorous stream of N2 gas
18
132.2
-
purified enzyme, electron donor: L-ascorbic acid, electron acceptor: cumene hydroperoxide
142.1
-
purified enzyme, electron donor: D-araboascorbic acid, electron acceptor: H2O2
172.8
-
purified enzyme, electron donor: L-ascorbic acid, electron acceptor: tert-butyl hydroperoxide
185.5
-
purified enzyme, electron donor: pyrogallol, electron acceptor: H2O2
254
-
purified enzyme, electron donor: L-ascorbic acid, electron acceptor: H2O2
456
-
after 285fold purification, in 50 mM potassium phosphate (pH 7.0), at 22°C
18
-
purified enzyme, electron donor: reductic acid, electron acceptor: H2O2
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
6.2
6.5
6.6
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
5 - 7.5
A7KIX5
pH 5: about 50% of maximal activity, pH 7.5: about 50% of maximal activity
5 - 8
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
25
32
45
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TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
20 - 55
-
20°C: about 65% of maximal activity, 55°C: about 40% of maximal activity
42
-
fusion protein with C-end tail of human alpha-synuclein, 50% residual activity
50.5
fusion forms with C-terminal hyperacidic tails, no notable loss of activity below
64.5
-
fusion protein with C-end tail of Arabidopsis tubulin TUA2, 50% residual activity
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
cultivated beet varieties, Huzar and Janosik, and their wild salt-tolerant relative Beta vulgaris ssp. maritima
-
-
brenda
growth at 14°C, decrease in membrane-bound enzyme activity, increase in total chlorophyll, growth at 22°C, increase in membrane-bound enzyme activity, and decrease in total chlorophyll. Before flowering, significantly negative correlation of membrane-bound enzyme with flowering time. Soluble enzyme shows irregular pattern of growth
-
-
brenda
wild type plants and plants overexpressing heat shock transcription factor 3, following heat stress, enzyme activity in wild type increased due to induction of a thermostable isoform probably identical with APX2, in transgenic plants, the thermostable isoform was detectable at normal temperature and persisted after severe heat stress at 44°C
-
-
brenda
Bright-Yellow 2 cells, decrease in enzyme amount and activity upon heat shock leading to programmed cell death
-
-
brenda
eight types of APx have been desribed in Oryza sativa, two cytosolic, OsAPx1 and OsAPx2, two putative peroxisomal, OsAPx3 and OsAPx4, and four chloroplastic isoforms OsAPx5, OsAPx6, OsAPx7 and OsAPx8
-
-
brenda
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
W6JMV3
during endormancy breaking, Apx activity decreases from deepest period to mid-breaking period, but then increases rapidly during ate-breaking period
brenda
A7KIX5
GhAPX1 is highly expressed in wild-type 5-day postanthesis fibres with much lower transcript levels in the fuzzless-lintless mutant ovules. GhAPX1 expression is upregulated in response to an increase in cellular H2O2 and ethylene
brenda
additional information
-
activity decreases during germination, strongly increases during callus induction and proliferation, and decreases during shoot and root induction
brenda
low expression level at blade sheath, high expression level at blade ear
brenda
high expression level. Isoform Apx1 expression level is higher compared to isoform Apx2; isoform Apx1 expression level is higher compared to isoform Apx2
brenda
U5RZT9
expression levels are higher in leaves than in roots or stems
brenda
-
total APX activity, on a fresh weight basis, is stimulated only at 2 mM methyl viologen at 24 h, but dropps at higher doses
brenda
-
young leaves contain low amounts of enzyme, in mature green leaves, small amounts of the enzyme are distributed in vascular systems, in particular in companion cells
brenda
-
activity decreases during germination, strongly increases during callus induction and proliferation, and decreases during shoot and root induction
brenda
of seedlings. NaCl-enhanced expression of OsAPx8 in rice roots is mediated through an accumulation of abscisic acid. Na+ but not Cl- is required for enhancing OsAPx8 expression. H2O2 is not involved in the regulation of NaCl-induced OsAPx8 expression in rice roots; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx1; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx2; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx3; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx4; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx5; of seedlings. No significant increase due to NaCl can be detected in the expression of OsAPx6; of seedlings. The expression of OsAPx7 is not affected by 150 mM and 200 mM NaCl, but is 40% decreased by 300 mM NaCl
brenda
U5RZT9
expression levels are higher in leaves than in roots or stems
brenda