ID   1.23.5.1
DE   violaxanthin de-epoxidase.
AN   VDE.
CA   all-trans-violaxanthin + 2 L-ascorbate = all-trans-zeaxanthin + 2 H2O +
CA   2 L-dehydroascorbate.
CC   -!- Along with EC 1.14.15.21, this enzyme forms part of the xanthophyll
CC       (or violaxanthin) cycle for controlling the concentration of
CC       zeaxanthin in chloroplasts.
CC   -!- It is activated by a low pH of the thylakoid lumen (produced by high
CC       light intensity).
CC   -!- Zeaxanthin induces the dissipation of excitation energy in the
CC       chlorophyll of the light-harvesting protein complex of photosystem
CC       II.
CC   -!- In higher plants the enzyme reacts with all-trans-diepoxides, such as
CC       violaxanthin, and all-trans-monoepoxides, but in the alga Mantoniella
CC       squamata, only the diepoxides are good substrates.
CC   -!- Formerly EC 1.10.99.3.
DR   Q39249, VDE_ARATH  ;  Q40251, VDE_LACSA  ;  Q9SM43, VDE_SPIOL  ;
DR   Q40593, VDE_TOBAC  ;
//