Vitamin A metabolism is important for vital processes such as vision, embryonic development, cell differentiation, and
membrane and skin protection. Beta-carotene 15,15-prime-dioxygenase (EC 1.13.11.21 ) is a key enzyme in
beta-carotene metabolism to vitamin A.
NCBI Summary:
Vitamin A metabolism is important for vital processes such as vision, embryonic development, cell differentiation, and membrane and skin protection. The protein encoded by this gene is a key enzyme in beta-carotene metabolism to vitamin A. It catalyzes the oxidative cleavage of beta,beta-carotene into two retinal molecules.
General function
Enzyme
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Comment
Expression regulated by
Comment
Ovarian localization
Granulosa, Luteal cells
Comment
Lindqvist A, et al 2002 reported biochemical properties of purified recombinant human beta
-carotene-15,15'-monooxygenase.
beta-Carotene-15,15-monooxygenase (BCO), formerly known as beta-carotene-15,15-dioxygenase,
catalyzes the first step in the synthesis of vitamin A from dietary carotenoids. A highly active
BCO enzyme was expressed and purified to homogeneity from baculovirus infected Sf9 insect cells.
The enzymes Km and Vmax for beta-carotene were 7 {micro}M and 10 nmol retinal/mg x min,
respectively, which corresponded to a turnover number (kcat) of 0.66 min(-1) and a catalytic
efficiency (kcat/Km) of ~10(5) M(-1) min(-1). The enzyme existed as a tetramer in solution and
substrate specificity analyses suggested that at least one unsubstituted beta-ionone ring half-site was
imperative for efficient cleavage of the carbon 1515-double bond in carotenoid substrates. High
levels of BCO mRNA were observed along the whole intestinal tract, the liver, and kidney, while
lower levels were present in the prostate, testis, ovary and skeletal muscle. The current data suggest
that the human BCO enzyme may, in addition to its well established role in the digestive system, also
play a role in peripheral vitamin A synthesis from plasma borne provitamin A carotenoids.
Follicle stages
Corpus luteum
Comment
Cloning of the bovine beta-carotene-15,15'-oxygenase and expression in gonadal tissues. Morales A et al. Beta-carotene-15,15'-oxygenase (betaCO), found mainly in intestinal mucosa and liver, is the enzyme responsible for cleaving beta-carotene into retinal, which can be used or stored at these sites or carried by the bloodstream to different target cells within the body. We isolated the cDNA for bovine betaCO and demonstrated its expression in gonadal tissues. A cDNA of 2130 base pairs (bp) was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE), using degenerate oligonucleotides; the deduced protein shared an identity of 75% with its homologues from other mammalian species. In order to evaluate the expression of this enzyme, we performed RT-PCR and in situ hybridizations in the ovary and testis of bovines. RT-PCR showed the expression of betaCO in testis, ovary, and cultured granulosa cells. In situ hybridization of complete ovary and testis revealed expression in granulosa cells and the corpus luteum in the ovary and in germinal and interstitial cells in the testis. These results suggest that beta-carotene could act as a local source of retinoids, which have been shown to be important during proliferation, differentiation, and maturation of both female and male germinal cells.