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Information on EC 1.14.20.5 - flavone synthase I
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EC Tree
1.14.20.5 flavone synthase IIUBMB Comments
The enzyme, which has been found in rice and in members of the Apiaceae (a plant family), is a member of the 2-oxoglutarate-dependent dioxygenases, and requires ascorbate and Fe2+ for full activity.
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Word Map
- 1.14.20.5
- apigenin
- flavonols
- naringenin
- chalcone
- luteolin
-
2-oxoglutarate-dependent
- apiaceae
-
3beta-hydroxylase
- parsley
- eriodictyol
- 2s-naringenin
- fnsiis
- crispum
- anthocyanidins
-
c-glycosides
-
petroselinum
- 7,4'-dihydroxyflavone
-
2s-flavanones
- dihydroquercetin
-
2-hydroxyflavanone
- genkwanin
- synthesis
- biotechnology
The enzyme appears in viruses and cellular organisms
Synonyms
flavone synthase, fns i, flavone synthase i, osfns, pfns-1, 
more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
EC 1.14.11.22
-
-
formerly
-
flavone synthase
flavone synthase I
FNS
FNS I
FSI
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
a flavanone + 2-oxoglutarate + O2 = a flavone + succinate + CO2 + H2O
-
-
-
-
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PATHWAY SOURCE
PATHWAYS
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SYSTEMATIC NAME
IUBMB Comments
flavanone,2-oxoglutarate:oxygen oxidoreductase (dehydrating)
The enzyme, which has been found in rice and in members of the Apiaceae (a plant family), is a member of the 2-oxoglutarate-dependent dioxygenases, and requires ascorbate and Fe2+ for full activity.
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CAS REGISTRY NUMBER
COMMENTARY
138263-98-6
-
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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
(2R)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
13% of the activity with (2S)-naringenin
-
-
?
(2S)-eriodictyol + 2-oxoglutarate + O2
luteolin + succinate + CO2 + H2O
-
-
-
-
ir
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + H2O + CO2
-
-
-
-
?
(2S)-pinocembrin + 2-oxoglutarate + O2
chrysin + succinate + CO2 + H2O
-
-
-
?
cis-dihydrokaempferol + 2-oxoglutarate + O2
kaempferol + succinate + CO2 + H2O
-
-
-
?
dihydrokaempferol + 2-oxoglutarate + O2
kaempferol + succinate + CO2 + H2O
the mutated enzymes L311F, Y240P, F146I, A120M and L311FA120M are all able to oxidize dihydrokaempferol to kaempferol, with respective catalytic activities relative to the wild type level of 355%, 104%, 86%, 162% and 175%. L311F substitution increases the flavonol synthase activity
-
-
?
eriodictyol + 2-oxoglutarate + O2
?
-
24% of the activity with naringenin
-
-
?
eriodictyol + 2-oxoglutarate + O2
luteolin + succinate + CO2 + H2O
-
-
-
?
hesperetin + 2-oxoglutarate + O2
3,5-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)-chromen-4-one + succinate + CO2 + H2O
-
26% of the activity with naringenin
-
-
?
homoeriodictyol + 2-oxoglutarate + O2
5,7,4'-trihydroxy-3'-methoxyflavone + succinate + CO2 + H2O
-
97% of the activity with naringenin
-
-
?
liquiritigenin + 2-oxoglutarate + O2
7,4'-dihydroxyflavone + succinate + CO2 + H2O
-
-
-
-
?
naringenin + 2-oxoglutarate + O2
apigenin + 2-hydroxynaringenin + succinate + CO2 + H2O
the enzyme catalyzes the conversion of naringenin to apigenin and 2-hydroxynaringenin. It is demonstrated that the enzyme is unable to catalyze the conversion of 2-hydroxynaringenin to apigenin. It is also confirmed that 2-hydroxynaringenin cannot be an intermediate product in the conversion of naringenin to apigenin, leaving the mechanism of conversion unknown
-
-
?
naringenin + O2 + 2-oxoglutarate
apigenin + succinate + CO2 + H2O
-
-
flavone 7-O-methyltransferase (POMT-7) converts apigenin into 7-O-methyl apigenin (genkwanin), 28°C, 10 mM potassium phosphate buffer with 1% glucose, pH 6.0, 5 mM ascorbate, 10 microM FeSO4, 100 microM substrate naringenin, 15 h incubation
-
?
S-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
purified enzyme, 3 h, 37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate (S- or R-naringenin) in 10 mM Tris/HCl buffer, pH 8.0
apigenin is converted by falvonoid 3',5'-hydroxylase to luteolin and tricetin
-
?
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
?
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
?
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
ir
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
?
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
?
naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
?
naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
-
?
naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
-
-
?
pinocembrin + 2-oxoglutarate + O2
chrysin + succinate + CO2 + H2O
-
-
-
?
pinocembrin + 2-oxoglutarate + O2
chrysin + succinate + CO2 + H2O
-
24% of the activity with naringenin
-
-
?
additional information
?
-
-
no activity with 5,7-dihydroxy-3',4',5'-O-trimethyl-flavanone,7-O-methyl-pinocembrin, 5-O-methyl-pinocembrin, 5,7-O-dimethyl-pinocembrin
-
-
?
additional information
?
-
no activity with eriodictyol or dihydroquercetin
-
-
?
additional information
?
-
-
no activity with eriodictyol or dihydroquercetin
-
-
?
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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
naringenin + O2 + 2-oxoglutarate
apigenin + succinate + CO2 + H2O
-
-
flavone 7-O-methyltransferase (POMT-7) converts apigenin into 7-O-methyl apigenin (genkwanin), 28°C, 10 mM potassium phosphate buffer with 1% glucose, pH 6.0, 5 mM ascorbate, 10 microM FeSO4, 100 microM substrate naringenin, 15 h incubation
-
?
S-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
-
purified enzyme, 3 h, 37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate (S- or R-naringenin) in 10 mM Tris/HCl buffer, pH 8.0
apigenin is converted by falvonoid 3',5'-hydroxylase to luteolin and tricetin
-
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Fe2+
Fe2+
-
required for full activity, cannot be replaced by Mn2+, Co2+ or Ni2+
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
ascorbate
-
required for full activity, can not be replaced as a reductant by 2-mercaptoethanol or dithiothreitol
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.02
S-naringenin
-
37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate in 10 mM Tris/HCl buffer, pH 8.0
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
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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
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
6
-
optimum for the combined action of both enzymes, next optimal pH is 8.0, then pH 7.0
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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pI VALUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
isoform FNS II-1, not inducible by Sinorhizobium meliloti or methyl jasmonate treatment. Ebnzyme has additional activity as flavone 2-hydroxylase
-
-
brenda
isoform FNS II-2, induced by Sinorhizobium meliloti or methyl jasmonate treatment in vascular tissue and root hair. Enzyme has additional activity as flavone 2-hydroxylase
-
-
brenda
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
relative DvFNS expressions in petals of different cultivars using realtime RT-PCR analysis, overview
brenda
-
induced by continous irradiation with ultraviolet/blue light for 20 h
brenda
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
malfunction
endogenous post-transcriptional gene silencing of flavone synthase results in high accumulation of anthocyanins in black dahlia cultivars
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UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). FNSI_PETCR
365
0
41024
Swiss-Prot
other Location (Reliability: 2)
A0A142FX92_LONJA
317
1
36456
TrEMBL
Secretory Pathway (Reliability: 1)
K7NW24_ANTMA
62
1
7053
TrEMBL
Mitochondrion (Reliability: 5)
F6M3L2_9LAMI
463
1
52584
TrEMBL
Secretory Pathway (Reliability: 5)
A0A7C9DTM1_OPUST
377
0
42166
TrEMBL
other Location (Reliability: 4)
A0A142FX96_9DIPS
315
1
36033
TrEMBL
Secretory Pathway (Reliability: 2)
A0A142FX93_LONJA
521
1
59210
TrEMBL
Secretory Pathway (Reliability: 1)
A0A7C8YC83_OPUST
132
0
14949
TrEMBL
other Location (Reliability: 2)
E9KBR9_SOYBN
527
1
59687
TrEMBL
Secretory Pathway (Reliability: 2)
K7P770_CYNCS
513
1
58371
TrEMBL
Secretory Pathway (Reliability: 3)
A0A142FX94_LONJA
326
1
37736
TrEMBL
Secretory Pathway (Reliability: 1)
A0A142FX95_9DIPS
519
1
58866
TrEMBL
Secretory Pathway (Reliability: 2)
A0A396GRS7_MEDTR
97
0
11164
TrEMBL
other Location (Reliability: 3)
A0A076U8J8_9MARC
361
0
39934
TrEMBL
other Location (Reliability: 4)
A0A142FX91_LONJA
521
1
59209
TrEMBL
Secretory Pathway (Reliability: 1)
A0A2Z4N9C7_SALMI
510
0
57340
TrEMBL
Mitochondrion (Reliability: 5)
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
38700
64000
-
SDS-PAGE, sum of flavone synthase and glutathione S-transferase (26000 Da)
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SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
A120M
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 162% of the catalytic activity relative to wild-type enzyme
F146I
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 86% of the catalytic activity relative to wild-type enzyme
F146I/A120M
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin
L311F
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 355% of the catalytic activity relative to wild-type enzyme
L311F/A120M
the double mutant catalyzes the formation of 2-hydroxynaringenin and apigenin, although the ratio of these two compounds iss lower than that generated by the wild type enzyme
L311F/F146I
the double mutant catalyzes the formation of 2-hydroxynaringenin and apigenin, although the ratio of these two compounds iss lower than that generated by the wild type enzyme
L311F/F146I/A120M
the activity of the triple mutant falls to about 5% of the wild type enzyme
L311F/Y240P
the double mutant exhibits less flavone synthase activity than either the wild type or the Y240P single mutant enzymes
Y240P
the mutant enzyme converts naringenin to apigenin without producing any 2-hydroxynaringenin. The mutant has a higher affinity (lower Km) with naringenin than the wild type enzyme, but the catalytic efficiency of the mutant is lower than that of wild type enzyme. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 104% of the catalytic activity relative to wild-type enzyme
Y240P/A120M
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 175% of the catalytic activity relative to wild-type enzyme
Y240P/F146I
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin
additional information
additional information
-
domain swapping experiments joining the N-terminus of flavanone 3beta-hydroxylase with the C-terminus of flavone synthase I and vice versa. Conversion of seven active site residues of flavanone 3beta-hydroxylase into the corresponding amino acids of flavone synthase I causes a nearly complete change in enzyme activity from flavanone 3beta-hydroxylase to flavone synthase I
additional information
transgenic seedlings of Arabidopsis thaliana accumulate substantial amounts of apigenin, and the apigenin level correlates with the abundance of enzyme mRNA
additional information
-
transgenic seedlings of Arabidopsis thaliana accumulate substantial amounts of apigenin, and the apigenin level correlates with the abundance of enzyme mRNA
additional information
-
use of enzyme for construction of a system for producing unnatural flavonoids and stilbenes in Escherichia coli by expression of the respective genes on three plasmids. Incubation of the recombinant Escherichia coli with exogenously supplied carboxylic acids leads to production of 87 different polyketides, including 36 unnatural flavonoids and stilbenes
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PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression of flavone synthase in Escherichia coli, purification on glutathione S-transferase (GST) affinity column
-
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression in Escherichia coli
expression in Saccharomyces cerevisiae
expression in yeast
RT-PCR cloning of flavone synthase cDNA, subcloning in pGEX 5X-2 for expression in Escherichia coli
-
the open reading frame of the flavone synthase gene PFNS-1 is cloned from Populus deltoids using RT-PCR, subcloned into Escherichia coli expression vector pGEX 5X-2, the flavone 7-O-methyltransferase into pRSF-Duet vector, both cotransformed into Escherichia coli BL21
-
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APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
biotechnology
-
product of the combined activity of flavone synthase and flavone 7-O-methyltransferase produces genkwanin (7-O-methyl apigenin) which exhibits antibacterial activity against Vibrio cholerae and Enterococcus faecalis, and anti-inflammatory activity, direct plant extracts result in limited amounts
synthesis
-
use of enzyme for construction of a system for producing unnatural flavonoids and stilbenes in Escherichia coli by expression of the respective genes on three plasmids. Incubation of the recombinant Escherichia coli with exogenously supplied carboxylic acids leads to production of 87 different polyketides, including 36 unnatural flavonoids and stilbenes
additional information
additional information
-
down-regulation by RNAi results in flavone depleted roots
additional information
-
down-regulation by RNAi results in significantly reduced nodulation when inoculated with Sinorhizobium meliloti
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Britsch, L.
Purification and characterization of flavone synthase I, a 2-oxoglutarate-dependent desaturase
Arch. Biochem. Biophys.
282
152-160
1990
Petroselinum crispum
brenda
Lukacin, R.; Matern, U.; Junghanns, K.T.; Heskamp, M.L.; Britsch, L.; Forkmann, G.; Martens, S.
Purification and antigenicity of flavone synthase I from irradiated parsley cells
Arch. Biochem. Biophys.
393
177-183
2001
Petroselinum crispum
brenda
Martens, S.; Forkmann, G.; Britsch, L.; Wellmann, F.; Matern, U.; Lukacin, R.
Divergent evolution of flavonoid 2-oxoglutarate-dependent dioxygenases in parsley
FEBS Lett.
544
93-98
2003
Petroselinum crispum (Q7XZQ8), Petroselinum crispum
brenda
Martens, S.; Forkmann, G.; Matern, U.; Lukacin, R.
Cloning of parsley flavone synthase I
Phytochemistry
58
43-46
2001
Petroselinum crispum
brenda
Schroeder, G.; Wehinger, E.; Lukacin, R.; Wellmann, F.; Seefelder, W.; Schwab, W.; Schroeder, J.
Flavonoid methylation: a novel 4'-O-methyltransferase from Catharanthus roseus, and evidence that partially methylated flavanones are substrates of four different flavonoid dioxygenases
Phytochemistry
65
1085-1094
2004
Petroselinum crispum
brenda
Leonard, E.; Yan, Y.; Lim, K.H.; Koffas, M.A.
Investigation of two distinct flavone synthases for plant-specific flavone biosynthesis in Saccharomyces cerevisiae
Appl. Environ. Microbiol.
71
8241-8248
2005
Petroselinum crispum (Q7XZQ8)
brenda
Leonard, E.; Chemler, J.; Lim, K.H.; Koffas, M.A.
Expression of a soluble flavone synthase allows the biosynthesis of phytoestrogen derivatives in Escherichia coli
Appl. Microbiol. Biotechnol.
70
85-91
2006
Petroselinum crispum
brenda
Miyahisa, I.; Funa, N.; Ohnishi, Y.; Martens, S.; Moriguchi, T.; Horinouchi, S.
Combinatorial biosynthesis of flavones and flavonols in Escherichia coli
Appl. Microbiol. Biotechnol.
71
53-58
2006
Petroselinum crispum (Q7XZQ8), Petroselinum crispum
brenda
Martens, S.; Mithoefer, A.
Flavones and flavone synthases
Phytochemistry
66
2399-2407
2005
Petroselinum crispum
brenda
Katsuyama, Y.; Funa, N.; Miyahisa, I.; Horinouchi, S.
Synthesis of unnatural flavonoids and stilbenes by exploiting the plant biosynthetic pathway in Escherichia coli
Chem. Biol.
14
613-621
2007