Information on EC 1.16.1.3 - aquacobalamin reductase

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

EC NUMBER
COMMENTARY hide
1.16.1.3
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RECOMMENDED NAME
GeneOntology No.
aquacobalamin reductase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
2 cob(II)alamin + NAD+ + 2 H2O = 2 aquacob(III)alamin + NADH + H+
show the reaction diagram
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
oxidation
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redox reaction
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reduction
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
Porphyrin and chlorophyll metabolism
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SYSTEMATIC NAME
IUBMB Comments
cob(II)alamin:NAD+ oxidoreductase
A flavoprotein.
CAS REGISTRY NUMBER
COMMENTARY hide
37256-39-6
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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Manually annotated by BRENDA team
freshwater fish
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
sea fish
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Manually annotated by BRENDA team
monkey
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Manually annotated by BRENDA team
frog
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Manually annotated by BRENDA team
pduS gene encodes a bifunctional cobalamin reductase that reduces cob(III)alamin to cob(II)alamin and, in presence of PduO adenosyltransferase, cob(II)alamin to cob(I)alamin
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
aquacobalamin + NADPH + H+
cob(II)alamin + NADP+
show the reaction diagram
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in addition to reductive activation of methionine synthase, methionine synthase reductase is able to reduce aquacobalamin to cob(II)alamin in the presence of NADPH. This reduction leads to stimulation of the conversion of apomethionine synthase and aquacobalamin to the methionine synthase holoenzyme
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?
cob(II)alamin + NADH + H+
cob(I)alamin + NAD+
show the reaction diagram
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reduction of cob(II)alamin requires the presence of PduO adenosyltransferase protein
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?
cob(III)alamin + NADH + H+
cob(II)alamin + NAD+
show the reaction diagram
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?
NADH + aquacob(III)alamin
NAD+ + cob(II)alamin
show the reaction diagram
NADPH + hydroxycobalamin
NADP+ + 5'-deoxyadenosylcobalamin
show the reaction diagram
additional information
?
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determination of aquacobalamin uptake as pro-coenzyme for cytosolic methionine synthase, EC 2.1.1.13, and mitochondrial methylmalonyl-CoA mutase, EC 5.4.99.2 into fibroblasts and glial cells
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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
aquacobalamin + NADPH + H+
cob(II)alamin + NADP+
show the reaction diagram
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in addition to reductive activation of methionine synthase, methionine synthase reductase is able to reduce aquacobalamin to cob(II)alamin in the presence of NADPH. This reduction leads to stimulation of the conversion of apomethionine synthase and aquacobalamin to the methionine synthase holoenzyme
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?
NADH + aquacob(III)alamin
NAD+ + cob(II)alamin
show the reaction diagram
additional information
?
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determination of aquacobalamin uptake as pro-coenzyme for cytosolic methionine synthase, EC 2.1.1.13, and mitochondrial methylmalonyl-CoA mutase, EC 5.4.99.2 into fibroblasts and glial cells
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
FMN
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flavoprotein, utilizes FAD better than FMN
NADPH
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about 12% of activity with NADH
additional information
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dithiothreitol cannot replace NADH as electron donor
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.032 - 0.099
aquacob(III)alamin
0.015
FAD
0.01 - 0.016
NADH
additional information
additional information
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.00028
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liver enzyme
0.0078
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substrate cob(II)alamin
0.0224
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mitochondrial, mutant cbl C
0.025 - 0.126
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mitochondrial, several mutants cbl C
0.029
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mitochondrial, mutant cbl A
0.037
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mitochondrial, wild-type
0.0385
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microsomal, mutant cbl A
0.0435
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microsomal, wild-type
0.044
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microsomal, mutant cbl C
0.069
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liver enzyme
0.091
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substrate cob(III)alamin
0.1
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mitochondrial, mutant cbl D
0.107
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mitochondrial, wild-type
0.111
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mitochondrial, mutant cbl E
0.118 - 0.186
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microsomal, several mutants cbl C
0.1275
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microsomal, liver
0.257
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microsomal, mutant cbl D
0.448
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microsomal, wild-type
0.458
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microsomal, mutant cbl E
0.578
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partially purified enzyme
3.3
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purified cytochrome b5/cytochromeB5 reductase complex from microsomes, substrate aquacobalamin
additional information
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6.6
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microsomal, liver
7.1
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mitochondrial
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
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x * 48400, calculated, x * 48000, SDS-PAGE
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
50
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5 min, about 80% loss of activity
60
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5 min, about 90% loss of activity
70
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5 min, complete loss of activity
GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
dithioerythritol stabilizes
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enzyme solutions rapidly lose activity, especially if frozen and thawed
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lyophilized preparations of cell-free extract stable to storage at -20°C for several weeks
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proteolytically unstable during purification of microsomes
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
both microsomal and mitochondrial; enzyme is probably part of the b-type cytochrome/cytochrome b5 reductase complex in rat mitochondria, identical elution behaviour in gel chromatography
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enzyme is probably part of the b-type cytochrome/cytochrome b5 reductase complex in rat mitochondria, identical elution behaviour in gel chromatography; partially
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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