Biology:Beta-carotene 15,15'-dioxygenase
| 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 | ||||||||
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 Generic protein structure example |
In enzymology, beta-carotene 15,15'-dioxygenase, (EC 1.13.11.63) is an enzyme with systematic name beta-carotene:oxygen 15,15'-dioxygenase (bond-cleaving).[1][2] In human it is encoded by the BCDO2 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.[3] The dioxygenase also asymmetrically cleaves beta-cryptoxanthin, trans-β-apo-8'-carotenal, beta-4'-apo-β-carotenal, alpha-carotene and gamma-carotene in decreasing order, creating one retinal molecule, all of these being substrates with a carbon chain greater than C30, with at least one unsubstituted β-ionone ring.[4]
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. A related enzyme is β-carotene 15,15'-monooxygenase, coded for by the gene BCMO1, which symmetrically cleaves β-carotene into two retinal molecules.[5][6]
In general, carnivores are poor converters of ionone-containing carotenoids, and pure carnivores such as felids (cats) lack beta-carotene 15,15'-dioxygenase and 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.[7]
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.[citation needed]
References
- ↑ "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. June 2009. doi:10.1074/jbc.M109.002618. PMID 19366683.
- ↑ "Retinal production from beta-carotene by beta-carotene 15,15'-dioxygenase from an unculturable marine bacterium". Biotechnology Letters 32 (7): 957–61. July 2010. doi:10.1007/s10529-010-0239-3. PMID 20229064.
- ↑ "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. November 2001. doi:10.1016/s0955-2863(01)00184-x. PMID 12031257. https://zenodo.org/record/1260161.
- ↑ "Substrate specificity of a recombinant chicken beta-carotene 15,15'-monooxygenase that converts beta-carotene into retinal". Biotechnology Letters 31 (3): 403–8. March 2009. doi:10.1007/s10529-008-9873-4. PMID 18979213.
- ↑ "Molecular aspects of β, β-carotene-9', 10'-oxygenase 2 in carotenoid metabolism and diseases". Exp Biol Med (Maywood) 241 (17): 1879–87. November 2016. doi:10.1177/1535370216657900. PMID 27390265.
- ↑ "Provitamin A metabolism and functions in mammalian biology". Am J Clin Nutr 96 (5): 1234S–44S. November 2012. doi:10.3945/ajcn.112.034629. PMID 23053549.
- ↑ "Meeting the Vitamin A Requirement: The Efficacy and Importance of β-Carotene in Animal Species". ScientificWorldJournal 2016: 7393620. 2016. doi:10.1155/2016/7393620. PMID 27833936.
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