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Blood plasma protein 3.5-5.0 ... beta-Carotene: Vitamin A dimer 3-25 ... C4 binding protein 1.8-3.2 ...
β-Carotene (beta-carotene) is an organic, strongly colored red-orange pigment abundant in fungi, [7] plants, and fruits. It is a member of the carotenes , which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 carbons .
Also downregulated is the enzyme beta-carotene 15,15'-dioxygenase (formerly known as beta-carotene 15,15'-monooxygenase) coded for by the BCMO1 gene, responsible for symmetrically cleaving β-carotene into retinal. [8] Absorbed β-carotene is either incorporated as such into chylomicrons or first converted to retinal and then retinol, bound to ...
Beta-carotene 15,15'-monooxygenase (BCO1; EC 1.14.99.36) from animals, which cleaves beta-carotene symmetrically at the central double bond to yield two molecules of retinal. [ 3 ] Beta-carotene-9',10'-dioxygenase (BCO2) from animals, which cleaves beta-carotene asymmetrically to apo-10'-beta-carotenal and beta-ionone, the latter being ...
Overconsumption of beta-carotene can only cause carotenosis, a harmless and reversible cosmetic condition in which the skin turns orange. Preformed vitamin A absorption and storage in the liver occur very efficiently until a pathologic condition develops. [21] When ingested, 70–90% of preformed vitamin A is absorbed and used. [21]
α-Carotene is produced when the all-trans lycopene first undergoes reaction with epsilon-LCY then a second reaction with beta-LCY; whereas β-carotene is produced by two reactions with beta-LCY. α- and β-Carotene are the most common carotenoids in the plant photosystems but they can still be further converted into xanthophylls by using beta ...
Finally, in certain disease states, the metabolism and conversion of carotenoids to retinol is slowed, which can lead to decreased clearance and increased plasma levels. Elevated serum beta-carotene does not necessarily result in carotenosis, but the latter is likely to show up when intake is more than 20 mg/day.
For most substances presented, the optimal levels are the ones normally found in the population as well. More specifically, optimal levels are generally close to a central tendency of the values found in the population. However, usual and optimal levels may differ substantially, most notably among vitamins and blood lipids, so these tables give ...