ENZYME

ENZYME entry: EC 1.13.11.51

Accepted Name

9-cis-epoxycarotenoid dioxygenase.

Alternative Name(s)

NCED.

Nine-cis-epoxycarotenoid dioxygenase.

VP14.

Reaction catalysed

A 9-cis-epoxycarotenoid + O(2) <=> 2-cis,4-trans-xanthoxin + a 12'-apo-carotenal
9-cis-violaxanthin + O(2) <=> 2-cis,4-trans-xanthoxin + (3S,5R,6S)-5,6-epoxy-3-hydroxy-5,6-dihydro-12'-apo-beta-caroten-12'-al
9'-cis-neoxanthin + O(2) <=> 2-cis,4-trans-xanthoxin + (3S,5R,6R)-5,6-dihydroxy-6,7-didehydro-5,6-dihydro-12'-apo-beta-caroten-12'-al

Cofactor(s)

Iron.

Comment(s)

Acts on 9-cis-violaxanthin and 9'-cis-neoxanthin but not on the all- trans isomers.
In vitro, it will cleave 9-cis-zeaxanthin.
Catalyzes the first step of abscisic-acid biosynthesis from carotenoids in chloroplasts, in response to water stress.
The other enzymes involved in the abscisic-acid biosynthesis pathway are EC 1.1.1.288, EC 1.2.3.14 and EC 1.14.13.93.

Cross-references

BRENDA

EC2PDB

ExplorEnz

PRIAM enzyme-specific profiles

KEGG Ligand Database for Enzyme Nomenclature

IUBMB Enzyme Nomenclature