Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Five carotenoids existing in the purple bacterium of Rhodobium marinum, lycopene, anhydrorhodovibrin, spirilloxanthin, rhodopin, and rhodovibrin, were isolated and purified. Their configurations in the chromophore region and conformations of the terminal part were determined by 1D, 2D 1H and 13C NMR spectroscopy. The semiempirical quantum chemical calculation AM1 was subsequently performed using the rough 3-D structures established by NOE correlations as an initial input. The final optimized structures are coincident with 1H-1H NOE correlations and match with the X-ray crystallographic data of carotenoids. The calculation results show that chemically symmetrical carotenoids have a Ci point group. The Ci point group of molecules was destroyed by asymmetrical terminal part although the polyene chain still keeps it roughly. The polyene region of investigated carotenoids are in all-trans with slightly twisted in-plane and slight out-plane forming s-shape carbon backbone due to the spatial interaction of the methyl groups. Terminal parts, on the other hand, have several stable conformers due to the freely rotatable single bonds, but they prefer to take extended conformations.
 ...
PMID:Conformation analysis of carotenoids in the purple bacterium Rhodobium marinum based on NMR spectroscopy and AM1 calculation. 1244 27

In animals, successful production of the visual chromophore (11-cis-retinal or derivatives thereof such as 11-cis-3-hydroxy-retinal) is essential for photoreceptor cell function and survival. These carotenoid-derived compounds must combine with a protein moiety (the opsin) to establish functional visual pigments. Evidence from cell culture systems has implicated that the retinal pigment epithelium protein of 65 kDa (RPE65) is the long-sought all-trans to 11-cis retinoid isomerase. RPE65 is structurally related to nonheme iron oxygenases that catalyze the conversion of carotenoids into retinoids. In vertebrate genomes, two carotenoid oxygenases and RPE65 are encoded, whereas in insect genomes only a single representative of this protein family, named NinaB (denoting neither inactivation nor afterpotential mutant B), is encoded. We here cloned and functionally characterized the ninaB gene from the great wax moth Galleria mellonella. We show that the recombinant purified enzyme combines isomerase and oxygenase (isomerooxygenase) activity in a single polypeptide. From kinetics and isomeric composition of cleavage products of asymmetrical carotenoid substrates, we propose a model for the spatial arrangement between substrate and enzyme. In Drosophila, we show that carotenoid-isomerooxygenase activity of NinaB is more generally found in insects, and we provide physiological evidence that carotenoids such as 11-cis-retinal can promote visual pigment biogenesis in the dark. Our study demonstrates that trans/cis isomerase activity can be intrinsic to this class of proteins and establishes these enzymes as key components for both invertebrate and vertebrate vision.
 ...
PMID:NinaB combines carotenoid oxygenase and retinoid isomerase activity in a single polypeptide. 1902 Jan