Disease relevance of NSC122756

• The simulations start from two simulated structures for the L550 intermediate of the photocycle, one involving a 13-cis retinal with strong torsions, the other a 13,14-dicis retinal, from which the M412 intermediate is initiated through proton transfer to Asp-85 [1].

High impact information on NSC122756

• Human AR and HSI AR were very efficient in the reduction of all- trans -, 9- cis - and 13- cis -retinal ( k (cat)/ K (m)=1100-10300 mM(-1).min(-1)), constituting the first cytosolic NADP(H)-dependent retinal reductases described in humans [2].
• We have previously characterized and cloned from kidney tissues the rat retinal dehydrogenase type 1 (RALDH1), which oxidizes all-trans and 9-cis retinal with high efficiency but is inactive with 13-cis retinal [3].
• The enzyme, mouse retinal reductase (RRD, also known as human 2,4-dienoyl-CoA reductase), reduces all-trans-retinal [V(m) = 40 nmol min(-1) (mg of protein)(-1); K(0.5) = 2.3 microM] and has 4- and 60-fold less activity with 13-cis-retinal and 9-cis-retinal, respectively [4].
• We arrived at the following explanation: The two bR isomers, one containing all-trans-retinal and the other 13-cis-retinal, respond differently to pH changes in the extravesicular and the intravesicular medium [5].
• In the case of the monomer, the extent of light adaptation, i.e., the fraction of BR molecules containing 13-cis-retinal as chromophore which is converted by illumination to the respective pigment with the all-trans isomer, is reduced by 50% or more, and the rate of dark adaptation is slowed down about 2.5 times [6].

Biological context of NSC122756

• The decay of the 13-cis-retinal extracted followed first-order kinetics with t 1/2 = 0.6 times the decay of the fastest measured component of the 400-420-nm decay [7].
• Biotransformation of all-trans-retinal, 13-cis-retinal, and 9-cis-retinal catalyzed by conceptal cytosol and microsomes [8].
• We report here our in vitro evaluation of the effects of three vitamin A analogues, 9-cis retinal, 13-cis RA and all-trans RA, on antibody production of PBMC from normal donors and patients with CVID [9].

Anatomical context of NSC122756

• A RR spectrum of the 13-cis-retinal complex "BR-548" could be deduced from spectra of the dark-adapted purple membrane [10].

Associations of NSC122756 with other chemical compounds

• Bacterially expressed JTC12 RALDH1 catalyzed conversion of all three retinal isomers, with a higher catalytic efficiency for 9-cis retinal than for all-trans and 13-cis retinal [3].
• Vitamin A1 aldehydes are specific natural substrates for ALDH-1; at pH 7.5, for all-trans- and 13-cis-retinal, Km = 1.1 and 0.37 micromolar, respectively, and kcat/Km is 50-100 times higher than that for acetaldehyde [11].

Gene context of NSC122756

• Formation of 7-cis- and 13-cis-retinal pigments by irradiating squid rhodopsin [12].

Analytical, diagnostic and therapeutic context of NSC122756

• Based on the heavy-atom coordinates determined by the electron microscopy for the seven main helical regions of bacteriorhodopsin with the all-trans retinal isomer, energy optimizations were carried out for helix bundles containing the all-trans retinal and 13-cis retinal chromophores, respectively [13].
• Analysis of retinal isomers with HPLC show that such an exposure produces a substance with 13-cis retinal as its chromophore and that it was significantly reduced after exposure to blue-green light [14].

References