Beta-carotene 15,15'-dioxygenase

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β-carotene 15,15'-dioxygenase
EC number1.13.11.63
CAS number37256-60-3
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
AliasesBCO1, BCDO, BCDO1, BCMO, BCMO1, BCO, beta-carotene oxygenase 1
External IDsOMIM: 605748 MGI: 1926923 HomoloGene: 41172 GeneCards: BCO1
EC number1.13.11.63
Gene location (Human)
Chromosome 16 (human)
Chr.Chromosome 16 (human)[1]
Chromosome 16 (human)
Genomic location for BCO1
Genomic location for BCO1
Band16q23.2Start81,238,689 bp[1]
End81,291,142 bp[1]
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 16: 81.24 – 81.29 MbChr 8: 117.1 – 117.13 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

In enzymology, β-carotene 15,15'-dioxygenase (EC is an enzyme with systematic name beta-carotene:oxygen 15,15'-dioxygenase (bond-cleaving).[5][6] In human it is encoded by the BCO1 gene. This enzyme catalyses the following chemical reaction

beta-carotene + O2 → 2 all-trans-retinal

This is a cleavage reaction which cleaves β-carotene, utilizes molecular oxygen, is enhanced by the presence of bile salts and thyroxine, and generates two molecules of retinal. In humans, the enzyme is present in the small intestine and liver.[7] It can also cleave beta-cryptoxanthin, apocarotenal, 4'-apo-β-carotenal, alpha-carotene and γ-carotene in decreasing order, all substrates greater than C30 with at least one unsubstituted β-ionone ring.[8]

This enzyme belongs to the (enzymatically-defined) family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. Other names in common use include β-carotene 15,15'-monooxygenase and β-carotene dioxygenase. Its previous EC numbers include (1975), (2001).

In general, carnivores are poor converters of ionone-containing carotenoids, and pure carnivores such as cats and ferrets lack beta-carotene 15,15'-monooxygenase and cannot convert any carotenoids to retinal (resulting in none of the carotenoids being forms of vitamin A for these species). They must have preformed vitamin A in their diet.

Beta-carotene 15,15'-dioxygenase belongs to the (similarity-defined) family of carotenoid oxygenases (InterProIPR004294). Enzymes of this family contain a Fe2+ active site, coordinated usually by four His residues.


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000135697 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000031845 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ Kim YS, Kim NH, Yeom SJ, Kim SW, Oh DK (June 2009). "In vitro characterization of a recombinant Blh protein from an uncultured marine bacterium as a beta-carotene 15,15'-dioxygenase". The Journal of Biological Chemistry. 284 (23): 15781–93. doi:10.1074/jbc.M109.002618. PMC 2708875. PMID 19366683.
  6. ^ Kim YS, Park CS, Oh DK (July 2010). "Retinal production from beta-carotene by beta-carotene 15,15'-dioxygenase from an unculturable marine bacterium". Biotechnology Letters. 32 (7): 957–61. doi:10.1007/s10529-010-0239-3. PMID 20229064. S2CID 2347505.
  7. ^ During A, Smith MK, Piper JB, Smith JC (November 2001). "beta-Carotene 15,15'-Dioxygenase activity in human tissues and cells: evidence of an iron dependency". The Journal of Nutritional Biochemistry. 12 (11): 640–647. doi:10.1016/s0955-2863(01)00184-x. PMID 12031257.
  8. ^ Kim YS, Oh DK (March 2009). "Substrate specificity of a recombinant chicken beta-carotene 15,15'-monooxygenase that converts beta-carotene into retinal". Biotechnology Letters. 31 (3): 403–8. doi:10.1007/s10529-008-9873-4. PMID 18979213. S2CID 21220270.

Further reading[edit]

  • Leuenberger MG, Engeloch-Jarret C, Woggon WD (2001). "The reaction mechanism of the enzyme-catalysed central cleavage of beta-carotene to retinal". Angew. Chem. 40 (14): 2614–2616. doi:10.1002/1521-3773(20010716)40:14<2613::aid-anie2613>;2-z.
  • Goodman DS, Huang HS, Kanai M, Shiratori T (1967). "The enzymatic conversion of all-trans beta-carotene into retinal". J. Biol. Chem. 242: 3543–3554.
  • Goodman DS, Huang HS, Shiratori T (May 1966). "Mechanism of the biosynthesis of vitamin A from beta-carotene". The Journal of Biological Chemistry. 241 (9): 1929–32. PMID 5946623.