Violaxanthin de-epoxidase

Violaxanthin de-epoxidase (, VDE) is an enzyme with systematic name violaxanthin:ascorbate oxidoreductase. This enzyme catalyses the following chemical reaction


 * violaxanthin + 2 L-ascorbate $$\rightleftharpoons$$ zeaxanthin + 2 L-dehydroascorbate + 2 H2O (overall reaction)
 * (1a) violaxanthin + L-ascorbate $$\rightleftharpoons$$ antheraxanthin + L-dehydroascorbate + H2O
 * (1b) antheraxanthin + L-ascorbate $$\rightleftharpoons$$ zeaxanthin + L-dehydroascorbate + H2O

Violaxanthin de-epoxidase is a part of the xanthophyll (or violaxanthin) cycle for controlling the concentration of zeaxanthin in chloroplasts.