EC Explorer

1.21.3.6

aureusidin synthase

(1) 2′,4,4′,6′-tetrahydroxychalcone 4′-O-β-D-glucoside + O₂ = aureusidin 6-O-β-D-glucoside + H₂O;;(2) 2′,3,4,4′,6′-pentahydroxychalcone 4′-O-β-D-glucoside + ½ O₂ = aureusidin 6-O-β-D-glucoside + H₂O;;(3) 2′,3,4,4′,6′-pentahydroxychalcone 4′-O-β-D-glucoside + O₂ = bracteatin 6-O-β-D-glucoside + H₂O

AmAS1

2′,4,4′,6′-tetrahydroxychalcone 4′-O-β-D-glucoside:oxygen oxidoreductase

320784-48-3

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-β-D-glucoside in vivo [4].

created 2003, modified 2012