beta-carotene 15,15'-dioxygenase;
blh (gene name)

Oxidoreductases;
Acting on single donors with O2 as oxidant and incorporation of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2;
With incorporation of two atoms of oxygen

beta-carotene:oxygen 15,15'-dioxygenase (bond-cleaving)

beta-carotene + O2 = 2 all-trans-retinal [RN:R00032]

R00032

beta-carotene [CPD:C02094];
O2 [CPD:C00007]

Requires Fe2+. The enzyme, which has been characterized from the uncultured marine bacterium 66A03, is involved in the proteorhodopsin system, which uses retinal as its chromophore. The enzyme cleaves beta-carotene symmetrically, producing two molecules of all-trans-retinal. Both atoms of the oxygen molecule are incorporated into the products. It requires a substrate greater than C35 that contains at least one unsubstituted beta-end group. cf. EC 1.14.99.36, beta-carotene 15,15-monooxygenase.

1  [PMID:19366683]

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.

J. Biol. Chem. 284 (2009) 15781-93.

2  [PMID:20229064]

Kim YS, Park CS, Oh DK

Retinal production from beta-carotene by beta-carotene 15,15'-dioxygenase from an unculturable marine bacterium.

Biotechnol. Lett. 32 (2010) 957-61.