Information on EC 2.1.1.76 - quercetin 3-O-methyltransferase

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The expected taxonomic range for this enzyme is: Gunneridae

EC NUMBER
COMMENTARY
2.1.1.76
-
RECOMMENDED NAME
GeneOntology No.
quercetin 3-O-methyltransferase
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
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
specific for quercetin, related enzymes bring about the 3-O-methylation of other flavonols, such as galangin and kaempferol
-
-
-
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
ordered sequential bi-bi mechanism
-
REACTION TYPE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
methyl group transfer
-
-
-
-
PATHWAY
KEGG Link
MetaCyc Link
Flavone and flavonol biosynthesis
-
methylquercetin biosynthesis
-
polymethylated quercetin biosynthesis
-
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.
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
3-OMT
-
-
-
-
flavonoid 3-methyltransferase
-
-
-
-
flavonol 3-O-methyltransferase
-
-
-
-
flavonol 3-O-methyltransferase
-
-
S-adenosyl-L-methionine:quercetin 3-O-methyltransferase
-
-
trimethylfavonol 3'/5'-OMT
-
-
CAS REGISTRY NUMBER
COMMENTARY
75603-21-3
-
ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
cDNA clone
SwissProt
Manually annotated by BRENDA team
Schwein ex Hooker
-
-
Manually annotated by BRENDA team
Citrofortunella microcarpa
calamondin orange, synonym Citrofortunella mitis
-
-
Manually annotated by BRENDA team
cultivar Money Maker
-
-
Manually annotated by BRENDA team
METALS and IONS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
K+
-
relative activity 115%
Mg2+
-
required for activity
Mn2+
-
relative activity 110%
INHIBITORS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
3'-O-methylmyricetin
-
i.e. laricitrin, inhibitory at substrate concentrations above 0.025 mM
-
3,6,7,3'-Tetramethylquercetagetin
-
noncompetitive inhibitor
3-methylquercetin
-
noncompetitive inhibitor with respect to both S-adenosyl-L-methionine and quercetin
p-chloromercuribenzoate
-
-
p-chloromercuribenzoate
-
1 mM, complete inhibition
S-adenosyl-L-homocysteine
-
competitive inhibitor with respect to S-adenosyl-L-methionine
ACTIVATING COMPOUND
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
2-mercaptoethanol
-
relative activity 105%
iodoacetamide
-
relative activity 105%
KM VALUE [mM]
KM VALUE [mM] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.00207
-
3'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
-
0.00998
-
7'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
-
0.013
-
kaempferol
-
30C
0.00055
-
myricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
0.007
-
myricetin
-
30C
0.0014
-
quercetin
-
-
0.012
-
quercetin
-
30C
0.01086
-
S-adenosyl-L-methionine
-
in 50 mM Tris-HCl (pH 7.5), at 22C
0.045
-
S-adenosyl-L-methionine
-
30C
0.07
-
S-adenosyl-L-methionine
-
-
TURNOVER NUMBER [1/s]
TURNOVER NUMBER MAXIMUM[1/s]
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
1.66
-
3'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
-
0.39
-
7'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
-
0.82
-
myricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
2.94
-
S-adenosyl-L-methionine
-
in 50 mM Tris-HCl (pH 7.5), at 22C
kcat/KM VALUE [1/mMs-1]
kcat/KM VALUE [1/mMs-1] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
930
-
3'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
0
50
-
7'-O-methylmyricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
0
1490
-
myricetin
-
in 50 mM Tris-HCl (pH 7.5), at 22C
13273
290
-
S-adenosyl-L-methionine
-
in 50 mM Tris-HCl (pH 7.5), at 22C
16346
SPECIFIC ACTIVITY [µmol/min/mg]
SPECIFIC ACTIVITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
additional information
-
-
53 pkat/mg
pH OPTIMUM
pH MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
pH RANGE
pH RANGE MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
7.2
9.3
-
about 50% of activity maximum at pH 7.2 and 9.3
pI VALUE
pI VALUE MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
6
-
-
chromatofocusing
MOLECULAR WEIGHT
MOLECULAR WEIGHT MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
35000
-
-
gel filtration
57000
-
-
gel filtration
65000
-
-
gel filtration
SUBUNITS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
?
-
x * 40000, SDS-PAGE
monomer
-
1 * 31000, SDS-PAGE
STORAGE STABILITY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
-15C, purified enzyme, 0.2 M potassium phosphate, pH 8.0, 20% glycerol, 5 mM dithiothreitol, stable for several months
-
4C, partially purified enzyme loses 80% of its activity over a period of 4-6 weeks
-