IUBMB Enzyme Nomenclature


Accepted name: β-carotene 15,15'-dioxygenase

Reaction: β-carotene + O2 = 2 all-trans-retinal

For diagram of reaction click here.

Other name(s): blh (gene name); BCO1 (gene name); BCDO (gene name); carotene dioxygenase; carotene 15,15'-dioxygenase; BCMO1 (misleading); β-carotene 15,15'-monooxygenase (incorrect)

Systematic name: β-carotene:oxygen 15,15'-dioxygenase (bond-cleaving)

Comments: Requires Fe2+. The enzyme cleaves β-carotene symmetrically, producing two molecules of all-trans-retinal. Both atoms of the oxygen molecule are incorporated into the products [8]. The enzyme can also process β-cryptoxanthin, 8'-apo-β-carotenal, 4'-apo-β-carotenal, α-carotene and γ-carotene in decreasing order. The presence of at least one unsubstituted β-ionone ring in a substrate greater than C30 is mandatory [5]. A prokaryotic enzyme has been reported from the uncultured marine bacterium 66A03, where it is involved in the proteorhodopsin system, which uses retinal as its chromophore [6,7].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Goodman, D.S., Huang, H.S. and Shiratori, T. Mechanism of the biosynthesis of vitamin A from β-carotene. J. Biol. Chem. 241 (1966) 1929-1932. [PMID: 5946623]

2. Goodman, D.S., Huang, H.S., Kanai, M. and Shiratori, T. The enzymatic conversion of all-trans β-carotene into retinal. J. Biol. Chem. 242 (1967) 3543-3554.

3. Yan, W., Jang, G.F., Haeseleer, F., Esumi, N., Chang, J., Kerrigan, M., Campochiaro, M., Campochiaro, P., Palczewski, K. and Zack, D.J. Cloning and characterization of a human β,β-carotene-15,15'-dioxygenase that is highly expressed in the retinal pigment epithelium. Genomics 72 (2001) 193-202. [PMID: 11401432]

4. Leuenberger, M.G., Engeloch-Jarret, C. and Woggon, W.D. The reaction mechanism of the enzyme-catalysed central cleavage of β-carotene to retinal. Angew. Chem. 40 (2001) 2614-2616. [PMID: 11458349]

5. Kim, Y.S. and Oh, D.K. Substrate specificity of a recombinant chicken β-carotene 15,15'-monooxygenase that converts β-carotene into retinal. Biotechnol. Lett. 31 (2009) 403-408. [PMID: 18979213]

6. Kim, Y.S., Kim, N.H., Yeom, S.J., Kim, S.W. and Oh, D.K. In vitro characterization of a recombinant Blh protein from an uncultured marine bacterium as a β-carotene 15,15'-dioxygenase. J. Biol. Chem. 284 (2009) 15781-15793. [PMID: 19366683]

7. Kim, Y.S., Park, C.S. and Oh, D.K. Retinal production from β-carotene by β-carotene 15,15'-dioxygenase from an unculturable marine bacterium. Biotechnol. Lett. 32 (2010) 957-961. [PMID: 20229064]

8. dela Seña, C., Riedl, K.M., Narayanasamy, S., Curley, R.W., Jr., Schwartz, S.J. and Harrison, E.H. The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase. J. Biol. Chem. 289 (2014) 13661-13666. [PMID: 24668807]

[EC created 2012 (EC created 1972 as EC, transferred 2001 to EC, incorporated 2015), modified 2016]

Return to EC 1.13.11 home page
Return to EC 1.13 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page