EC Number   |
General Information |
Reference |
|---|
   1.21.3.6 | 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 |
744988 |
| 1.21.3.6 | physiological function |
expression in Nicotiana tabacum and Lactuca sativa leads to plants that display a functionally active chalcone-flavanone biosynthetic pathway. Leaves of the resulting transgenic plants develop a yellow hue and display higher superoxide dismutase inhibiting and oxygen radical absorbance capacity activities than control leaves |
720645 |
| 1.21.3.6 | physiological function |
PPOs have a role in postharvest browning, secondary reactions of PPO-generated o-quinones with cellular nucleophiles leading to the familiar discoloration of fresh products and plant materials. Aurones (aureusidin and bracteatin) are formed from 2,4,6,4-tetrahydroxychalcone or 2,4,6,3,4-pentahydroxychalcone upon incubation with extracts of yellow snapdragon flowers through activity of aureusidin (or aurone) synthase |
744988 |
