KEGG ENZYME: 1.21.3.6

ENZYME: 1.21.3.6

Entry

EC 1.21.3.6                 Enzyme

Name

aureusidin synthase;
AmAS1

Class

Oxidoreductases;
Catalysing the reaction X-H + Y-H = X-Y;
With oxygen as acceptor

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)

R08008 R08009 R08010;
(other) R07224 R07225 R08005

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

ec00941

Flavonoid biosynthesis

ec01110

Biosynthesis of secondary metabolites

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 290:1163-6 (2000)
DOI:10.1126/science.290.5494.1163

Sequence

[ag:BAB20048]

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 499:107-11 (2001)
DOI:10.1016/S0014-5793(01)02529-7

Sequence

[ag:BAB20048]

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 160:229-236 (2001)
DOI:10.1016/S0168-9452(00)00385-X