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{{Short description|Mammalian protein found in Homo sapiens}}

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In enzymology, beta-carotene 15,15’-dioxygenase, ({{EC number|1.13.11.63| CAS_number = 37256-60-3}}) is an enzyme with systematic name beta-carotene:oxygen 15,15’-dioxygenase (bond-cleaving).JOURNAL, Kim YS, Kim NH, Yeom SJ, Kim SW, Oh DK, 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, 19366683, 2708875, 10.1074/jbc.M109.002618, free, JOURNAL, Kim YS, Park CS, Oh DK, Retinal production from beta-carotene by beta-carotene 15,15’-dioxygenase from an unculturable marine bacterium, Biotechnology Letters, 32, 7, 957–61, July 2010, 20229064, 10.1007/s10529-010-0239-3, 2347505, In human it is encoded by the BCO1 gene. This enzyme catalyses the following chemical reaction 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.JOURNAL, During A, Smith MK, Piper JB, Smith JC, 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, 12031257, 10.1016/s0955-2863(01)00184-x,zenodo.org/record/1260161, 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.JOURNAL, Kim YS, Oh DK, 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, 18979213, 10.1007/s10529-008-9873-4, 21220270, 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.JOURNAL, Wu L, Guo X, Wang W, Medeiros DM, Clarke SL, Lucas EA, Smith BJ, Lin D, 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, 27390265, 5068469, 10.1177/1535370216657900, JOURNAL, von Lintig J, Provitamin A metabolism and functions in mammalian biology, Am J Clin Nutr, 96, 5, 1234S–44S, November 2012, 23053549, 3471205, 10.3945/ajcn.112.034629, 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.JOURNAL, Green AS, Fascetti AJ, Meeting the Vitamin A Requirement: The Efficacy and Importance of β-Carotene in Animal Species, ScientificWorldJournal, 2016, 7393620, 2016, 27833936, 5090096, 10.1155/2016/7393620, free, 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|date=April 2022}}

References

{{reflist}}{{Monooxygenases}}{{Dioxygenases}}{{Enzymes}}{{1.13-enzyme-stub}}