Information on EC 1.21.3.6 - aureusidin synthase

for references in articles please use BRENDA:EC1.21.3.6
Word Map on EC 1.21.3.6
Please wait a moment until all data is loaded. This message will disappear when all data is loaded.
Specify your search results
Select one or more organisms in this record:

The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.21.3.6
-
RECOMMENDED NAME
GeneOntology No.
aureusidin synthase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
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',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
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dehydrogenation
-
-
-
-
hydroxylation
-
-
-
-
oxidation
-
-
-
-
oxidative cyclization
-
-
-
-
oxygenation
-
-
-
-
redox reaction
-
-
-
-
reduction
-
-
-
-
PATHWAY
BRENDA Link
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 act mainly on the 4'-O-beta-D-glucoside in vivo [4].
CAS REGISTRY NUMBER
COMMENTARY hide
320784-48-3
-
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
-
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
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
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
2 2',3,4,4',6'-pentahydroxychalcone + O2
bracteatin + 2 H2O
show the reaction diagram
-
-
-
-
?
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
2',3,4,4',6'-pentahydroxychalcone + O2
aureusidin + bracteatin + H2O
show the reaction diagram
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
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
2',4,4',6'-tetrahydroxychalcone 4'-beta-D-glucopyranoside + O2
aureusidin 6-beta-D-glucopyranoside + H2O
show the reaction diagram
2,4,6,4-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
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
?
-
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
2 2',3,4,4',6'-pentahydroxychalcone + O2
bracteatin + 2 H2O
show the reaction diagram
-
-
-
-
?
2',3,4,4',6'-pentahydroxychalcone + 1/2 O2
aureusidin + bracteatin + H2O
show the reaction diagram
2',4,4',6'-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
2,4,6,4-tetrahydroxychalcone + O2
aureusidin + H2O
show the reaction diagram
additional information
?
-
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
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
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
H2O2
-
inhibits oxidation of 2',3,4,4',6'-pentahydroxychalcone
Phenylthiourea
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
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]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.001
Phenylthiourea
-
pH 6.6
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
578
-
purified enzyme
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
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 hide
LITERATURE
30
-
assay at
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
additional information
-
analysis of spatial and temporal expression; not in stem and leaf
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
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
COMMENTARY hide
LITERATURE
?
-
x * 39000, mature form, SDs-PAGE
monomer
-
1 * 39000, SDS-PAGE
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
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
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
-
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
107fold; to homogeneity
-
native enzyme to homogeneity from yellow snapdragon flower buds
-
to homogeneity
-
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in Nicotiana tabacum and Lactuca sativa
-
gene AmAS1, DNA and amino acid sequence determination and analysis
-
gene AS1, DNA and amino acid sequence determination and analyis
-
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
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
nutrition
-
nutritional qualities of leafy vegetables can be enhanced through the introduction of aurone biosynthetic pathways