Information on EC 2.1.1.76 - quercetin 3-O-methyltransferase

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The expected taxonomic range for this enzyme is: Magnoliophyta

EC NUMBER
COMMENTARY hide
2.1.1.76
-
RECOMMENDED NAME
GeneOntology No.
quercetin 3-O-methyltransferase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone = S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
methyl group transfer
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-
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
Flavone and flavonol biosynthesis
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methylquercetin biosynthesis
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polymethylated quercetin biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
S-adenosyl-L-methionine:3,5,7,3',4'-pentahydroxyflavone 3-O-methyltransferase
Specific for quercetin. Related enzymes bring about the 3-O-methylation of other flavonols, such as galangin and kaempferol.
CAS REGISTRY NUMBER
COMMENTARY hide
75603-21-3
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Citrofortunella microcarpa
calamondin orange, synonym Citrofortunella mitis
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-
Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
cultivar Money Maker
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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
S-adenosyl-L-methionine + 3',5'-O-dimethylmyricetin
S-adenosyl-L-homocysteine + 3,3',5'-O-trimethylmyricetin
show the reaction diagram
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18% activity compared to myricetin
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-
?
S-adenosyl-L-methionine + 3'-O-methylmyricetin
S-adenosyl-L-homocysteine + 3,3'-O-dimethylmyricetin
show the reaction diagram
S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone
S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone
show the reaction diagram
S-adenosyl-L-methionine + 3-O-methylquercetin
S-adenosyl-L-homocysteine + ?
show the reaction diagram
-
3% activity compared to myricetin
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-
?
S-adenosyl-L-methionine + 4'-O-methylkaempferol
S-adenosyl-L-homocysteine + 3,4'-O-dimethylkaempferol
show the reaction diagram
-
11% activity compared to myricetin
-
-
?
S-adenosyl-L-methionine + 7-methylquercetin
?
show the reaction diagram
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i.e. rhamnetin, 30% of the activity with quercetin
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-
?
S-adenosyl-L-methionine + 7-O-methylmyricetin
S-adenosyl-L-homocysteine + 3,7-O-dimethylquercetin
show the reaction diagram
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104% activity compared to myricetin
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-
?
S-adenosyl-L-methionine + galangin
S-adenosyl-L-homocysteine + ?
show the reaction diagram
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60% of the activity with quercetin
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-
?
S-adenosyl-L-methionine + isorhamnetin
S-adenosyl-L-homocysteine + ?
show the reaction diagram
-
88% of the activity with quercetin
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-
?
S-adenosyl-L-methionine + kaempferol
S-adenosyl-L-homocysteine + 3-O-methyl-kaempferol
show the reaction diagram
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93% of the activity with quercetin
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-
?
S-adenosyl-L-methionine + kaempferol
S-adenosyl-L-homocysteine + 3-O-methylkaempferol
show the reaction diagram
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53% activity compared to myricetin
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-
?
S-adenosyl-L-methionine + myricetin
S-adenosyl-L-homocysteine + 3-O-methyl-myricetin
show the reaction diagram
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46% of the activity with quercetin
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?
S-adenosyl-L-methionine + myricetin
S-adenosyl-L-homocysteine + 3-O-methylmyricetin
show the reaction diagram
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100% activity
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?
S-adenosyl-L-methionine + myricetin
S-adenosyl-L-homocysteine + ?
show the reaction diagram
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-
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?
S-adenosyl-L-methionine + quercetin
S-adenosyl-L-homocysteine + 3-O-methyl-quercetin
show the reaction diagram
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-
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?
S-adenosyl-L-methionine + quercetin
S-adenosyl-L-homocysteine + 3-O-methylquercetin
show the reaction diagram
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121% activity compared to myricetin
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?
S-adenosyl-L-methionine + tamarixetin
S-adenosyl-L-homocysteine + ?
show the reaction diagram
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85% of the activity with quercetin
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?
additional information
?
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the enzyme does not methylate 3',4',5'-O-trimethylmyricetin, 3,7,3',4'-O-methylquercetin, 3-methylquercetin, and 3,7,4'-O-trimethylkaempferol. The enzyme transfers a methyl group only to the 3-position hydroxyl
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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
S-adenosyl-L-methionine + 3,5,7,3',4'-pentahydroxyflavone
S-adenosyl-L-homocysteine + 3-methoxy-5,7,3',4'-tetrahydroxyflavone
show the reaction diagram
additional information
?
-
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the enzyme does not methylate 3',4',5'-O-trimethylmyricetin, 3,7,3',4'-O-methylquercetin, 3-methylquercetin, and 3,7,4'-O-trimethylkaempferol. The enzyme transfers a methyl group only to the 3-position hydroxyl
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
K+
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relative activity 115%
Mg2+
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required for activity
Mn2+
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relative activity 110%
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
3'-O-methylmyricetin
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i.e. laricitrin, inhibitory at substrate concentrations above 0.025 mM
3,6,7,3'-Tetramethylquercetagetin
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noncompetitive inhibitor
3-methylquercetin
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noncompetitive inhibitor with respect to both S-adenosyl-L-methionine and quercetin
N-ethylmaleimide
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p-chloromercuribenzoate
S-adenosyl-L-homocysteine
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competitive inhibitor with respect to S-adenosyl-L-methionine
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
2-mercaptoethanol
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relative activity 105%
iodoacetamide
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relative activity 105%
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.00207
3'-O-methylmyricetin
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in 50 mM Tris-HCl (pH 7.5), at 22C
0.00998
7-O-methylmyricetin
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in 50 mM Tris-HCl (pH 7.5), at 22C
0.013
kaempferol
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30C
0.00055 - 0.007
myricetin
0.0014 - 0.012
quercetin
0.01086 - 0.07
S-adenosyl-L-methionine
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
1.66
3'-O-methylmyricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
0.39
7-O-methylmyricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
0.82
myricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
2.94
S-adenosyl-L-methionine
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
930
3'-O-methylmyricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
15242
50
7-O-methylmyricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
42169
1490
myricetin
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
484
290
S-adenosyl-L-methionine
Solanum habrochaites
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in 50 mM Tris-HCl (pH 7.5), at 22C
24
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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53 pkat/mg
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7.2 - 9.3
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about 50% of activity maximum at pH 7.2 and 9.3
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.4
calculated from amino acid sequence
6
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chromatofocusing
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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glandular trichome
Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
35000
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gel filtration
57000
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gel filtration
65000
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gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
monomer
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1 * 31000, SDS-PAGE
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-15C, purified enzyme, 0.2 M potassium phosphate, pH 8.0, 20% glycerol, 5 mM dithiothreitol, stable for several months
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4C, partially purified enzyme loses 80% of its activity over a period of 4-6 weeks
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
MonoQ column chromatography
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partially
recombinant protein, expressed in E. coli BL21
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli
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pET-19b vector, cDNA clone overexpressed in Escherichia coli BL21
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
quercetin 3-O-methyltransferase is induced 1.3fold by aluminium stress (treatment with 0.02 mM AlK (SO4)2)
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