Reaction: β-carotene + O2 = 2 retinal
For diagram of reaction click here and mechanism click here.
Other name(s): β-carotene 15,15'-dioxygenase, carotene dioxygenase; carotene 15,15'-dioxygenase
Systematic name: β-carotene:oxygen 15,15'-oxidoreductase (bond-cleaving)
Comments: Requires bile salts and Fe(II). The reaction proceeds in three stages, epoxidation of the 15,15'-double bond, hydration of the double bond leading to ring opening, and oxidative cleavage of the diol formed [cf. EC 1.14.15.6, cholesterol monooxygenase (side-chain-cleaving)]. Thus only one atom of the dioxygen is incorporated into retinal. Formerly EC 1.13.11.21 as it was considered to be a dioxygenase.
Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 37256-60-3
References:
1. 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. Int. Ed. 40 (2001) 2614-2616. [PMID: 11458349]
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. 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]