Beta-carotene 15,15'-dioxygenase

In enzymology, β-carotene 15,15'-dioxygenase (EC 1.13.11.63) 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

β-carotene 15,15'-dioxygenase
Identifiers
EC number	1.13.11.63
CAS number	37256-60-3
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

BCO1
Identifiers
Aliases	BCO1, BCDO, BCDO1, BCMO, BCMO1, BCO, beta-carotene oxygenase 1
External IDs	OMIM: 605748 MGI: 1926923 HomoloGene: 41172 GeneCards: BCO1
EC number	1.13.11.63
Gene location (Human) Chr. Chromosome 16 (human)[1] Band 16q23.2 Start 81,238,689 bp[1] End 81,291,142 bp[1]
Gene location (Mouse) Chr. Chromosome 8 (mouse)[2] Band 8|8 E1 Start 117,095,854 bp[2] End 117,133,720 bp[2]
Gene ontology Molecular function • oxidoreductase activity • beta-carotene 15,15'-monooxygenase activity • oxidoreductase activity, acting on single donors with incorporation of molecular oxygen, incorporation of two atoms of oxygen • dioxygenase activity • metal ion binding • retinal isomerase activity • carotenoid dioxygenase activity Cellular component • cytosol Biological process • retinol metabolic process • vitamin A biosynthetic process • oxidation-reduction process • retinoid metabolic process • retinal metabolic process • beta-carotene metabolic process • carotene catabolic process Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	53630	63857
Ensembl	ENSG00000135697	ENSMUSG00000031845
UniProt	Q9HAY6	Q9JJS6
RefSeq (mRNA)	NM_017429	NM_001163028 NM_021486
RefSeq (protein)	NP_059125	NP_001156500 NP_067461
Location (UCSC)	Chr 16: 81.24 – 81.29 Mb	Chr 8: 117.1 – 117.13 Mb
PubMed search	[3]	[4]
Wikidata
View/Edit Human View/Edit Mouse

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 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 1.13.11.21 (1975), 1.14.99.36 (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 contains Fe²⁺.

References

1. GRCh38: Ensembl release 89: ENSG00000135697 - Ensembl, May 2017
2. 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.
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.

Further reading

• 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: 2614–2616. doi:10.1002/1521-3773(20010716)40:14<2613::aid-anie2613>3.0.co;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.