Beta-carotene 15,15'-dioxygenase

β-carotene 15,15'-dioxygenase
Identifiers
EC no.	1.13.11.63
CAS no.	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; OMA:BCO1 - orthologs
EC number	1.13.11.63
Gene location (Human) Chr. Chromosome 16 (human) Band 16q23.2 Start 81,238,689 bp End 81,291,142 bp
Gene location (Mouse) Chr. Chromosome 8 (mouse) Band 8|8 E1 Start 117,822,593 bp End 117,860,459 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in retinal pigment epithelium jejunal mucosa duodenum palpebral conjunctiva Epithelium of choroid plexus rectum mucosa of transverse colon pancreatic ductal cell gallbladder islet of Langerhans Top expressed in gastrula yolk sac seminiferous tubule decidua intestinal villus hepatobiliary system liver spermatid embryo embryo More reference expression data BioGPS n/a
Gene ontology Molecular function oxidoreductase activity beta-carotene 15,15'-dioxygenase 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 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: 117.82 – 117.86 Mb PubMed search
Wikidata
View/Edit Human View/Edit Mouse

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). 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. 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.

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 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 belongs to the (similarity-defined) family of carotenoid oxygenases (InterPro: IPR004294). Enzymes of this family contain a Fe²⁺ active site, coordinated usually by four His residues.

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 (14): 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.