Information on EC 1.16.5.1 - ascorbate ferrireductase (transmembrane)

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.16.5.1
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RECOMMENDED NAME
GeneOntology No.
ascorbate ferrireductase (transmembrane)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
ascorbate[side 1] + Fe(III)[side 2] = monodehydroascorbate[side 1] + Fe(II)[side 2]
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
Fe(III):ascorbate oxidorectuctase (electron-translocating)
A diheme cytochrome that transfers electrons across a single membrane, such as the outer membrane of the enterocyte, or the tonoplast membrane of the plant cell vacuole. Acts on hexacyanoferrate(III) and other ferric chelates.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
metabolism
physiological function
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Dcytb plays a physiological role in both iron and copper uptake, through divalent metal transporter1 and copper transporter 1, respectively
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
ascorbate[side 1] + Fe(CN)3[side 2]
monodehydroascorbate[side 1] + ?
show the reaction diagram
ascorbate[side 1] + Fe(III)-citrate[side 2]
?
show the reaction diagram
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?
ascorbate[side 1] + Fe(III)-EDTA[side 2]
?
show the reaction diagram
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?
ascorbate[side 1] + Fe(III)[side 2]
monodehydroascorbate[side 1] + Fe(II)[side 2]
show the reaction diagram
ascorbate[side 1] + Fe3+-EDTA[side 2]
monodehydroascorbate[side 1] + ?
show the reaction diagram
ascorbate[side 1] + ferricyanide[side 2]
?
show the reaction diagram
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?
ascorbate[side 1] + nitroblue tetrazolium[side 2]
dehydroascorbate + ?
show the reaction diagram
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?
bathocuprionedisulfonate[side 1] + Cu(II)-nitrilotriacetic acid[side 2]
Cu(I)-bathocuproinedisulfonate
show the reaction diagram
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?
cupric-histidine[side 1] + ?
?
show the reaction diagram
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?
ferric citrate[side 1] + ?
?
show the reaction diagram
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?
ferrozine[side 1] + Fe(III)-nitrilotriacetic acid[side 2]
Fe(II)-ferrozine
show the reaction diagram
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?
ferrozine[side 1] + Fe3+-EDTA[side 2]
?
show the reaction diagram
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?
additional information
?
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Dcytb has the capacity to reduce both iron and copper complexes
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
ascorbate[side 1] + Fe(III)[side 2]
monodehydroascorbate[side 1] + Fe(II)[side 2]
show the reaction diagram
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?
cupric-histidine[side 1] + ?
?
show the reaction diagram
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?
ferric citrate[side 1] + ?
?
show the reaction diagram
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?
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
ascorbate
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
Diethylpyrocarbonate
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the electron accepting ability of bovine cytochrome b561 from ascorbate is selectively inhibited by the treatment with diethylpyrocarbonate
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
ascorbate
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cytb561 ferric reductase activity is greatly enhanced by the addition of ascorbate
dehydroascorbate
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preloading cells with dehydroascorbate greatly increases both ferric and cupric reductase activities of Dcytb
L-galactono-gamma-lactone
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0152 - 0.0231
Cu(II)-nitrilotriacetic acid[side 2]
0.074 - 0.0921
Fe(III)-nitrilotriacetic acid[side 2]
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
26900
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calculated from amino acid sequence
27000
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LCytb, SDS-PAGE
27800
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CGCytb, SDS-PAGE
30000
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SDS-PAGE
31500
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DCytb, SDS-PAGE
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
high-resolution crystal structures of cytochrome b561 from Arabidopsis thaliana in both substrate-free and substrate-bound states is reported. Cyt b561 forms a homodimer, with each protomer consisting of six transmembrane helices and two heme groups
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purified by affinity chromatography and gel filtration
using Ni-NTA chromatography
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Dcytb-EGFP is expressed in tetracycline-off Madin-Darby canine kidney cells
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expressed as a His-tagged fusion protein in Escherichia coli
expressed in a Saccharomyces cerevisiae strain S288C DELTAfre1DELTAfre2 mutant, which lacks almost all of its plasma membrane ferrireductase activity
expressed in Escherichia coli
expressed in Saccharomyces cerevisiae, strain YPH499
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expressed in the Saccharomyces cerevisiae mutant strain S288C DELTAfre1DELTAfre2 that lacks plasma membrane ferrireductase activity
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expressed in Xenopus laevis oocytes
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
expression of Dcytb-EGFP is knocked down by addition of 20 ng/ml doxycycline
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iron-deficient patients have significantly higher ferric reductase activity and duodenal and plasma ascorbate concentrations than do control subjects
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
F105W/H106E
mutations on the noncytoplasmic side only still allows the oxidized Cyt b561 to be reduced by ascorbate
K81A/R150A
mutations on the cytoplasmic side only still allows the oxidized Cyt b561 to be reduced by ascorbate
K81A/R150A/F105W/H106E
mutant carrying ascorbate-binding mutations on both cytoplasmic and noncytoplasmic sides, completely loses its ability to be reduced by ascorbate
Y115W
mutations on the noncytoplasmic side only still allows the oxidized Cyt b561 to be reduced by ascorbate
Y140W
mutations on the cytoplasmic side only still allows the oxidized Cyt b561 to be reduced by ascorbate
D38A
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the mutant shows increased Fe(CN)3 reductase activity compared to the wild type enzyme
E117A
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the mutant shows decreased Fe(CN)3 reductase activity compared to the wild type enzyme
E196A
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the mutant shows decreased Fe(CN)3 reductase activity compared to the wild type enzyme
F44A
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the mutation reduces the Fe(CN)3 reductase activity by about 45%
H105A
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the mutant shows increased Fe(CN)3 reductase activity compared to the wild type enzyme
H112A
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the mutant shows decreased Fe(CN)3 reductase activity compared to the wild type enzyme
H117A
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the mutation completely abrogates the Fe(CN)3 reductase activity of the enzyme
H156A
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the mutation completely abrogates the Fe(CN)3 reductase activity of the enzyme
H47A
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the mutation completely abrogates the Fe(CN)3 reductase activity of the enzyme
H83A
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the mutation completely abrogates the Fe(CN)3 reductase activity of the enzyme
M51A
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the mutant shows increased Fe(CN)3 reductase activity compared to the wild type enzyme
N106A
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the mutant shows increased Fe(CN)3 reductase activity compared to the wild type enzyme
P48A
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the mutant shows increased reductase activity compared to the wild type enzyme
Q131A
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the activity of the mutant is reduced significantly to 45% of that of the wild type
R149A
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the mutation results in a 75% loss in activity compared to the wild type enzyme
R67A
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the mutation results in an almost complete loss of the Fe(CN)3 reductase activity
S115A
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the ferrireductase activity in the mutant is reduced to 50%
W119A
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the ferrireductase activity in the mutant is reduced to 17%; the mutant shows decreased Fe(CN)3 reductase activity compared to the wild type enzyme
Y190A
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the mutant shows increased Fe(CN)3 reductase activity compared to the wild type enzyme
Y66A
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the mutation results in an almost complete loss of the Fe(CN)3 reductase activity