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ENZYME entry: EC

Accepted Name
Beta-carotene 4-ketolase.
Alternative Name(s)
Beta-c-4 oxygenase.
Beta-carotene ketolase.
Reaction catalysed
  • Beta-carotene + 2 reduced acceptor + 2 O(2) <=> echinenone + 2 acceptor + 3 H(2)O
  • Echinenone + 2 reduced acceptor + 2 O(2) <=> canthaxanthin + 2 acceptor + 3 H(2)O
  • The enzyme, studied from algae, plants, fungi, and bacteria, adds an oxo group at position 4 of a carotenoid beta ring.
  • It is involved in the biosynthesis of carotenoids such as astaxanthin and flexixanthin.
  • The enzymes does not act on beta rings that are hydroxylated at position 3, such as in zeaxanthin (cf. EC
  • The enzyme from the yeast Xanthophyllomyces dendrorhous is bifuntional and also catalyzes the activity of EC
PRIAM enzyme-specific profiles1.14.99.63
KEGG Ligand Database for Enzyme Nomenclature1.14.99.63
IUBMB Enzyme Nomenclature1.14.99.63
MEDLINEFind literature relating to
Rhea expert-curated reactions1.14.99.63
Q39982, CRTW_HAELA;  Q44261, CRTW_PARS1;  P54972, CRTW_PARSN;  

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