Information on EC 1.21.3.6 - aureusidin synthase

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The expected taxonomic range for this enzyme is: Antirrhinum majus

EC NUMBER
COMMENTARY
1.21.3.6
-
RECOMMENDED NAME
GeneOntology No.
aureusidin synthase
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + 1/2 O2 = aureusidin 6-O-beta-D-glucoside + H2O
show the reaction diagram
(2)
-
-
-
2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + 1/2 O2 = aureusidin 6-O-beta-D-glucoside + H2O
show the reaction diagram
mechanism
-
2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + O2 = bracteatin 6-O-beta-D-glucoside + H2O
show the reaction diagram
(3)
-
-
-
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside + O2 = aureusidin 6-O-beta-D-glucoside + H2O
show the reaction diagram
(1)
-
-
-
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside + O2 = aureusidin 6-O-beta-D-glucoside + H2O
show the reaction diagram
mechanism
-
REACTION TYPE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
dehydrogenation
-
-
-
-
hydroxylation
-
-
-
-
oxidation
-
-
-
-
oxidative cyclization
-
-
-
-
oxygenation
-
-
-
-
redox reaction
-
-
-
-
reduction
-
-
-
-
PATHWAY
KEGG Link
MetaCyc Link
aurone biosynthesis
-
Flavonoid biosynthesis
-
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 mainly act on the 4'-O-beta-D-glucoside in vivo [4].
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
synthase, aureusidin
-
-
-
-
additional information
-
-
-
CAS REGISTRY NUMBER
COMMENTARY
320784-48-3
-
ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
cv. Yellow Butterfly; gene AmAS1; snapdragon
-
-
Manually annotated by BRENDA team
cv. Yellow Butterfly; snapdragon
-
-
Manually annotated by BRENDA team
wild-type and natural mutants sulfurea and violacea showing increased aurone production in petals and reduced aurone production, resp.
-
-
Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
best substrate
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
best substrate
products are formed in a 6:1 ratio
ir
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
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
show the reaction diagram
-
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
show the reaction diagram
-
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + bracteatin 6-beta-D-glucopyranoside + H2O
show the reaction diagram
-
-
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
show the reaction diagram
-
-
products provide the yellow colour of flowers
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
no formation of 2-(alpha-hydroxybenzyl)coumaranone intermediate, key intermediate in the general flonoid metabolism
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
show the reaction diagram
-
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
show the reaction diagram
-
-
-
ir
butein + O2
sulfuretin + 3',4',5',6'-tetrahydroxyaurone + H2O
show the reaction diagram
-
-
products are formed in a 23:1 ratio
ir
isoliquiritigenin + O2
sulfuretin + H2O
show the reaction diagram
-
-
-
ir
additional information
?
-
-
no activity with L-tyrosine, L-DOPA, 4-coumaric acid, caffeic acid, naringenin, eriodictyol, 4,4',6'-trihydroxyaurone, and aureusidin, absolutely specific for chalcones, 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
?
-
-
pathway, overview
-
-
-
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
-
-
-
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
-
-
ir
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
-
key intermediate in the general flonoid metabolism
-
ir
additional information
?
-
-
pathway, overview
-
-
-
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
-
-
-
METALS and IONS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
Cu2+
-
copper-containing enzyme, bound via histidine residues in the active site
INHIBITORS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
H2O2
-
inhibits oxidation of 2',3,4,4',6'-pentahydroxychalcone
Phenylthiourea
-
competitive inhibition
ACTIVATING COMPOUND
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
H2O2
-
activates oxidation of 2',4,4',6'-tetrahydroxychalcone
H2O2
-
absolutely required; activates oxidation of 2',4,4',6'-tetrahydroxychalcone; optimal at 5 mM
KM VALUE [mM]
KM VALUE [mM] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.0157
-
2',3,4,4',6'-pentahydroxychalcone
-
pH 6.6
0.0081
-
2',3,4,4',6'-pentahydroxychalcone 4'-beta-D-glucopyranoside
-
pH 6.6
0.0043
-
2',4,4',6'-tetrahydroxychalcone
-
pH 6.6
0.0039
-
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside
-
pH 6.6
0.0147
-
butein
-
pH 6.6
0.0025
-
isoliquiritigenin
-
pH 6.6
Ki VALUE [mM]
Ki VALUE [mM] Maximum
INHIBITOR
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.001
-
Phenylthiourea
-
pH 6.6
SPECIFIC ACTIVITY [µmol/min/mg]
SPECIFIC ACTIVITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
578
-
-
purified enzyme
pH OPTIMUM
pH MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
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
TEMPERATURE OPTIMUM MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
30
-
-
assay at
SOURCE TISSUE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
SOURCE
-
enzyme expression
Manually annotated by BRENDA team
-
inner epidermis of the face and throat of lower petal
Manually annotated by BRENDA team
additional information
-
analysis of spatial and temporal expression; not in stem and leaf
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT ACCESSION NO.
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
Manually annotated by BRENDA team
MOLECULAR WEIGHT
MOLECULAR WEIGHT MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
40000
-
-
mature enzyme, gel filtration
additional information
-
-
enzyme is processed to the mature from a 65 kDa precursor protein by cleavage of the N-terminal part
SUBUNITS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
?
-
x * 39000, mature form, SDs-PAGE
monomer
-
1 * 39000, SDS-PAGE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
glycoprotein
-
-
proteolytic modification
-
vacuolar targeting sequence is encoded within a 53-residue N-terminal sequence, but not in the C-terminal sequence of the precursor
Purification/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
107fold; to homogeneity
-
to homogeneity
-
Cloned/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
gene AmAS1, DNA and amino acid sequence determination and analysis
-
ENGINEERING
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
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
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
APPLICATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
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