KEGG   ENZYME: 1.21.3.6Help
Entry
EC 1.21.3.6                 Enzyme                                 

Name
aureusidin synthase;
AmAS1
Class
Oxidoreductases;
Acting on X-H and Y-H to form an X-Y bond;
With oxygen as acceptor
BRITE hierarchy
Sysname
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside:oxygen oxidoreductase
Reaction(IUBMB)
(1) 2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside + O2 = aureusidin 6-O-beta-D-glucoside + H2O [RN:R08008];
(2) 2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + 1/2 O2 = aureusidin 6-O-beta-D-glucoside + H2O [RN:R08010];
(3) 2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + O2 = bracteatin 6-O-beta-D-glucoside + H2O [RN:R08009]
Reaction(KEGG)
Substrate
2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside [CPD:C16407];
O2 [CPD:C00007];
2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside [CPD:C16408]
Product
aureusidin 6-O-beta-D-glucoside [CPD:C16409];
H2O [CPD:C00001];
bracteatin 6-O-beta-D-glucoside [CPD:C16410]
Comment
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].
History
EC 1.21.3.6 created 2003, modified 2012
Pathway
Flavonoid biosynthesis
Orthology
K13079  
aureusidin synthase
Reference
1  [PMID:11073455]
  Authors
Nakayama T, Yonekura-Sakakibara K, Sato T, Kikuchi S, Fukui Y, Fukuchi-Mizutani M, Ueda T, Nakao M, Tanaka Y, Kusumi T, Nishino T.
  Title
Aureusidin synthase: a polyphenol oxidase homolog responsible for flower coloration.
  Journal
Science. 290 (2000) 1163-6.
  Organism
Antirrhinum majus
  Sequence
[up:Q9FRX6]
Reference
2  [PMID:11418122]
  Authors
Nakayama T, Sato T, Fukui Y, Yonekura-Sakakibara K, Hayashi H, Tanaka Y, Kusumi T, Nishino T.
  Title
Specificity analysis and mechanism of aurone synthesis catalyzed by aureusidin synthase, a polyphenol oxidase homolog responsible for flower coloration.
  Journal
FEBS. Lett. 499 (2001) 107-11.
  Organism
Antirrhinum majus
  Sequence
[up:Q9FRX6]
Reference
3  [PMID:11164594]
  Authors
Sato T, Nakayama T, Kikuchi S, Fukui Y, Yonekura-Sakakibara K, Ueda T, Nishino T, Tanaka Y, Kusumi T.
  Title
Enzymatic formation of aurones in the extracts of yellow snapdragon flowers.
  Journal
Plant. Sci. 160 (2001) 229-236.
  Organism
Antirrhinum majus
Reference
4  [PMID:16832053]
  Authors
Ono E, Fukuchi-Mizutani M, Nakamura N, Fukui Y, Yonekura-Sakakibara K, Yamaguchi M, Nakayama T, Tanaka T, Kusumi T, Tanaka Y.
  Title
Yellow flowers generated by expression of the aurone biosynthetic pathway.
  Journal
Proc. Natl. Acad. Sci. U. S. A. 103 (2006) 11075-80.
  Organism
Antirrhinum majus
  Sequence
[up:Q9FRX6]
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
320784-48-3

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