Any feedback?
Information on EC 1.21.3.6 - aureusidin synthase and Organism(s) Antirrhinum majus and UniProt Accession Q9FRX6
for references in articles please use BRENDA:EC1.21.3.6Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
EC Tree
1.21.3.6 aureusidin synthaseIUBMB Comments
A copper-containing glycoprotein that plays a key role in the yellow coloration of flowers such as Antirrhinum majus (snapdragon). The enzyme is a homologue of plant polyphenol oxidase and catalyses two separate chemical transformations, i.e. 3-hydroxylation and oxidative cyclization (2',-dehydrogenation). H2O2 activates reaction (1) but inhibits reaction (2). Originally considered to act on the phenol but now thought to act mainly on the 4'-O-beta-D-glucoside in vivo .
Specify your search results
Word Map
- 1.21.3.6
- yellow
-
aurones
- flower
- snapdragon
- flavonoid
- majus
-
antirrhinum
-
ornamental
- polyphenol
-
bright
- petal
- anthocyanin
-
colour
- catechol
- oxidases
-
cyclization
- vacuole
- cosmos
- agriculture
- nutrition
The taxonomic range for the selected organisms is: Antirrhinum majus
The enzyme appears in selected viruses and cellular organisms
The enzyme appears in selected viruses and cellular organisms
Reaction Schemes
+
=
+
Synonyms
aureusidin synthase, amas1, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
synthase, aureusidin
-
-
-
-
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside + O2 = aureusidin 6-O-beta-D-glucoside + H2O
mechanism
-
2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + 1/2 O2 = aureusidin 6-O-beta-D-glucoside + H2O
mechanism
-
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
oxygenation
-
-
-
-
redox reaction
-
-
-
-
oxidation
-
-
-
-
reduction
-
-
-
-
hydroxylation
-
-
-
-
dehydrogenation
-
-
-
-
oxidative cyclization
-
-
-
-
SYSTEMATIC NAME
IUBMB Comments
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside:oxygen oxidoreductase
A copper-containing glycoprotein that plays a key role in the yellow coloration of flowers such as Antirrhinum majus (snapdragon). The enzyme is a homologue of plant polyphenol oxidase [1] and catalyses two separate chemical transformations, i.e. 3-hydroxylation and oxidative cyclization (2',-dehydrogenation). H2O2 activates reaction (1) but inhibits reaction (2). Originally considered to act on the phenol but now thought to act mainly on the 4'-O-beta-D-glucoside in vivo [4].
CAS REGISTRY NUMBER
COMMENTARY
320784-48-3
-
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
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + bracteatin 6-beta-D-glucopyranoside + H2O
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
butein + O2
sulfuretin + 3',4',5',6-tetrahydroxyaurone + H2O
-
-
products are formed in a 23:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
-
-
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
-
best substrate
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
-
best substrate
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
-
2210% activity compared to 2',4,4',6'-tetrahydroxychalcone
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
-
2-6fold higher activity than with 2',4,4',6'-tetrahydroxychalcone
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + bracteatin 6-beta-D-glucopyranoside + H2O
-
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + bracteatin 6-beta-D-glucopyranoside + H2O
-
-
products are formed in a 5:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + bracteatin 6-beta-D-glucopyranoside + H2O
-
-
products provide the yellow colour of flowers
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
-
no formation of 2-(alpha-hydroxybenzyl)coumaranone intermediate
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
-
key intermediate in the general flonoid metabolism
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
-
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
-
-
-
ir
additional information
?
-
substrate specificity allows elucidation of a likely mechanism of aurone formation from 2,4,6,4-tetrahydroxychalcone or PHC involving both tyrosinase and catechol oxidase activities of the Antirrhinum majus PPO, pathway overview. Starting with THC, tyrosinase and catechol oxidase activity, EC 1.14.18.1, result in 3-hydroxylation and formation of the corresponding o-quinone. Whether aureusidine synthase PPO carries out the 3-hydroxylation reaction in vivo, or whether a cytochrome P450 chalcone 3-hydroxylase is also involved is not definitively established. Aureusidine synthase likely forms the same quinone from 2',3,4,4',6'-pentahydroxychalcone without the need for the 3-hydroxylation step. The resulting quinone is predicted to undergo a 2-step non-enzyme mediated rearrangement to form aureusidin
-
-
?
additional information
?
-
-
no activity with L-tyrosine, L-DOPA, 4-coumaric acid, caffeic acid, naringenin, eriodictyol, 4,4',6'-trihydroxyaurone, and aureusidin
-
-
?
additional information
?
-
-
no activity with 2'-hydroxychalcone, 4-hydroxychalcone, 2',3,4,4',6'-pentahydroxychalcone 3-glucoside, and 2',6'-dihydroxy-4,4'-dimethoxychalcone
-
-
?
additional information
?
-
-
enzyme shows no 3',4'-dehydrogenase activity towards aureusidin
-
-
?
additional information
?
-
-
enzyme shows no 3',4'-dehydrogenase activity towards aureusidin
-
-
?
additional information
?
-
-
chalcone-specific polyphenol oxidase specialized for aurone biosynthesis
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
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
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
-
key intermediate in the general flonoid metabolism
-
ir
additional information
?
-
substrate specificity allows elucidation of a likely mechanism of aurone formation from 2,4,6,4-tetrahydroxychalcone or PHC involving both tyrosinase and catechol oxidase activities of the Antirrhinum majus PPO, pathway overview. Starting with THC, tyrosinase and catechol oxidase activity, EC 1.14.18.1, result in 3-hydroxylation and formation of the corresponding o-quinone. Whether aureusidine synthase PPO carries out the 3-hydroxylation reaction in vivo, or whether a cytochrome P450 chalcone 3-hydroxylase is also involved is not definitively established. Aureusidine synthase likely forms the same quinone from 2',3,4,4',6'-pentahydroxychalcone without the need for the 3-hydroxylation step. The resulting quinone is predicted to undergo a 2-step non-enzyme mediated rearrangement to form aureusidin
-
-
?
additional information
?
-
-
chalcone-specific polyphenol oxidase specialized for aurone biosynthesis
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
additional information
?
-
-
enzyme plays a key role in the yellow coloration of flowers, enzyme is a homologue of plant polyphenol oxidase
-
-
?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
copper
two copper atoms, CuA and CuB, are located in the active site and each is coordinated by three histidine residues. CuA is coordinated by His87, His108, and His117 residues, while CuB is coordinated by His241, His245 and His275
Cu2+
-
copper-containing enzyme, bound via histidine residues in the active site
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
Phenylthiourea
modeling of enzyme-phenylthiourea complex. The inhibitor binds with the hydrophobic pocket of the dinuclear copper center. The phenyl ring of Phe262 and the imidazole ring of His245 form hydrophobic interactions with the aromatic ring of the inhibitor. The sulfur atom of the inhibitor replaces the hydroxo-bridge, which is essential for catalysis
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.0081
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside
-
pH 6.6
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
5 - 7
-
broad, formation of aureusidin from 2',3,4,4',6'-pentahydroxychalcone
5.4
-
3-hydroxylation and cyclization of 2',4,4',6'-tetrahydroxychalcone
additional information
-
at pH values above pH 7.0, 2',4,4',6'-tetrahydroxychalcone undergoes a very rapid isomerization to the inactive naringenin
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
chalcones are 4-O-glucosylated in the cytoplasm and thereafter transported to the vacuole, where the enzyme converts them to aurone 6-O-glucosides
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
metabolism
substrate specificity allows elucidation of a likely mechanism of aurone formation from 2,4,6,4-tetrahydroxychalcone or PHC involving both tyrosinase and catechol oxidase activities of the Antirrhinum majus PPO, pathway overview. Starting with THC, tyrosinase and catechol oxidase activity, EC 1.14.18.1, result in 3-hydroxylation and formation of the corresponding o-quinone. Whether aureusidine synthase PPO carries out the 3-hydroxylation reaction in vivo, or whether a cytochrome P450 chalcone 3-hydroxylase is also involved is not definitively established. Aureusidine synthase likely forms the same quinone from 2',3,4,4',6'-pentahydroxychalcone without the need for the 3-hydroxylation step. The resulting quinone is predicted to undergo a 2-step non-enzyme mediated rearrangement to form aureusidine
physiological function
physiological function
expression in Nicotiana tabacum and Lactuca sativa leads to plants that display a functionally active chalcone-flavanone biosynthetic pathway. Leaves of the resulting transgenic plants develop a yellow hue and display higher superoxide dismutase inhibiting and oxygen radical absorbance capacity activities than control leaves
physiological function
PPOs have a role in postharvest browning, secondary reactions of PPO-generated o-quinones with cellular nucleophiles leading to the familiar discoloration of fresh products and plant materials. Aurones (aureusidin and bracteatin) are formed from 2,4,6,4-tetrahydroxychalcone or 2,4,6,3,4-pentahydroxychalcone upon incubation with extracts of yellow snapdragon flowers through activity of aureusidin (or aurone) synthase
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). AS1_ANTMA
562
1
64044
Swiss-Prot
other Location (Reliability: 1)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
39000
additional information
-
enzyme is processed to the mature from a 65 kDa precursor protein by cleavage of the N-terminal part
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
proteolytic modification
-
vacuolar targeting sequence is encoded within a 53-residue N-terminal sequence, but not in the C-terminal sequence of the precursor
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
homology modeling using grenache polyphenol oxidase and sweet potato catechol oxidase as templates. The structure is folded into 15alpha-helices and 5 beta-sheets, and mostly composed by loops. The core of the enzyme is formed by a four-helix-bundle, and the helical bundle accommodates the dinuclear copper center. The cysteine residues Cys11, Cys25, Cys26, and Cys88 are highly conserved, and form disulfide bridges
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
additional information
-
fusion of putative enzyme propepetide to green fluorescent protein, localization within the vacuole
additional information
-
fusion protein of enzyme N-terminal 60 amino acids with red fluorescence protein localizes within the vacuole
additional information
-
natural enzyme mutants sulfurea and violacea showing increased aurone production in petals and reduced aurone production, resp. Enzyme and aureusidin 7-O-glucosyltransferase transcript abundance and spatial pattern is similar in wild-type and mutants. Recessive mutant line CFR1011 with greatly reduced aurone production also shows no change in transcript abundance or any point mutantions in the coding sequences of enzyme or aureusidin 7-O-glucosyltransferase
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
APPLICATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
nutrition
nutritional qualities of leafy vegetables can be enhanced through the introduction of aurone biosynthetic pathways
agriculture
-
coexpression of enzyme and chalcone 4-O-glucosyltransferase is sufficient for accumulation of aureusidin 6-O-glucoside in transgenic flowers. Additional down-regulation of anthocyanin biosynthesis by RNAi results in yellow flowers
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Nakayama, T.; Yonekura-Sakakibara, K.; Sato, T.; Kikuchi, S.; Fukui, Y.; Fukuchi-Mizutani, M.; Ueda, T.; Nakao, M.; Tanaka, Y.; Kusumi, T.; Nishino, T.
Aureusidin synthase: a polyphenol oxidase homolog responsible for flower coloration
Science
290
1163-1166
2000
Antirrhinum majus
Nakayama, T.; Sato, T.; Fukui, Y.; Yonekura-Sakakibara, K.; Hayashi, H.; Tanaka, Y.; Kusumi, T.; Nishino, T.
Specificity analysis and mechanism of aurone synthesis catalyzed by aureusidin synthase, a polyphenol oxidase homolog responsible for flower coloration
FEBS Lett.
499
107-111
2001
Antirrhinum majus
Sato, T.; Nakayama, T.; Kikuchi, S.; Fukui, Y.; Yonekura-Sakakibara, K.; Ueda, T.; Nishino, T.; Tanaka, Y.; Kusumi, T.
Enzymatic formation of aurones in the extracts of yellow snapdragon flowers
Plant Sci.
160
229-236
2001
Antirrhinum majus
Davies, K.M.; Marshall, G.B.; Bradley, J.M.; Schwinn, K.E.; Bloor, S.J.; Winefield, C.S.; Martin, C.R.
Characterisation of aurone biosynthesis in Antirrhinum majus
Physiol. Plant.
128
593-603
2006
Antirrhinum majus
Ono, E.; Hatayama, M.; Isono, Y.; Sato, T.; Watanabe, R.; Yonekura-Sakakibara, K.; Fukuchi-Mizutani, M.; Tanaka, Y.; Kusumi, T.; Nishino, T.; Nakayama, T.
Localization of a flavonoid biosynthetic polyphenol oxidase in vacuoles
Plant J.
45
133-143
2006
Antirrhinum majus
Ono, E.; Fukuchi-Mizutani, M.; Nakamura, N.; Fukui, Y.; Yonekura-Sakakibara, K.; Yamaguchi, M.; Nakayama, T.; Tanaka, T.; Kusumi, T.; Tanaka, Y.
Yellow flowers generated by expression of the aurone biosynthetic pathway
Proc. Natl. Acad. Sci. USA
103
11075-11080
2006
Antirrhinum majus
Shakya, R.; Ye, J.; Rommens, C.M.
Altered leaf colour is associated with increased superoxide-scavenging activity in aureusidin-producing transgenic plants
Plant Biotechnol. J.
10
1046-1055
2012
Antirrhinum majus (Q9FRX6), Antirrhinum majus
Elumalai, P.; Liu, H.L.
Homology modeling and dynamics study of aureusidin synthase--an important enzyme in aurone biosynthesis of snapdragon flower
Int. J. Biol. Macromol.
49
134-142
2011
Antirrhinum majus (Q9FRX6), Antirrhinum majus
EXTERNAL LINKS (specific for EC-Number 1.21.3.6)
Use of this online version of BRENDA is free under the CC BY 4.0 license. See terms of use for full details.
Release 2023.1 (January 2023)
Legal
Curated at
Member of
