3917-40-6Relevant articles and documents
Accurate measurements of 13C-13C J-couplings in the rhodopsin chromophore by double-quantum solid-state NMR spectroscopy
Lai, Wai Cheu,McLean, Neville,Gansmueller, Axel,Verhoeven, Michiel A.,Antonioli, Gian Carlo,Carravetta, Marina,Duma, Luminita,Bovee-Geurts, Petra H. M.,Johannessen, Ole G.,De Groot, Huub J. M.,Lugtenburg, Johan,Emsley, Lyndon,Brown, Steven P.,Brown, Richard C. D.,DeGrip, Willem J.,Levitt, Malcolm H.
, p. 3878 - 3879 (2007/10/03)
A new double-quantum solid-state NMR pulse sequence is presented and used to measure one-bond 13C-13C J-couplings in a set of 13C2-labeled rhodopsin isotopomers. The measured J-couplings reveal a perturbation of the electronic structure at the terminus of the conjugated chain but show no evidence for protein-induced electronic perturbation near the C11-C12 isomerization site. This work establishes NMR methodology for measuring accurate 1JCC values in noncrystalline macromolecules and shows that the measured J-couplings may reveal local electronic perturbations of mechanistic significance. Copyright
Preparation and biological activity of 13-substituted retinoic acids
Wada, Akimori,Fukunaga, Kouki,Ito, Masayoshi,Mizuguchi, Yukari,Nakagawa, Kimie,Okano, Toshio
, p. 3931 - 3942 (2007/10/03)
13-Demethyl or 13-substituted all-E- and 9Z-retinoic acids were synthesized using a palladium-catalyzed coupling reaction of enol triflates and tributylstannylolefins. Their biological activities were then measured. The 13-ethyl analogs exhibited approximately one-half of the antiproliferative and differentiation-inducing activity of ATRA in HL-60 cells. In contrast, in the 9Z-derivatives, all analogs, except for the 13-butyl derivatives, showed apoptosis-inducing activity.
Constraints of opsin structure on the ligand-binding site: Studies with ring-fused retinals
Hirano, Takahiro,Lim, In Taek,Kim, Don Moon,Zheng, Xiang-Guo,Yoshihara, Kazuo,Oyama, Yoshiaki,Imai, Hiroo,Shichida, Yoshinori,Ishiguro, Masaji
, p. 606 - 615 (2007/10/03)
Ring-fused retinal analogs were designed to examine the hulatwist mode of the photoisomerization of the 9-cis retinylidene chromophore. Two 9-cis retinal analogs, the C11-C13 five-membered ring-fused and the C12-C14 five-membered ring-fused retinal derivatives, formed the pigments with opsin. The C11-C13 ring-fused analog was isomerized to a relaxed all-trans chromophore (λmax > 400 nm) at even - 269°C and the Schiff base was kept protonated at 0°C. The C12-C14 ring-fused analog was converted photochemically to a bathorhodopsin-like chromophore (λmax = 583 nm) at -196°C, which was further converted to the deprotonated Schiff base at 0°C. The model-building study suggested that the analogs do not form pigments in the retinal-binding site of rhodopsin but form pigments with opsin structures, which have larger binding space generated by the movement of transmembrane helices. The molecular dynamics simulation of the isomerization of the analog chromophores provided a twisted C11-C12 double bond for the C12-C14 ring-fused analog and all relaxed double bonds with a highly twisted C10-C11 bond for the C11-C13 ring-fused analog. The structural model of the C11-C13 ring-fused analog chromophore showed a characteristic flip of the cyclohexenyl moiety toward transmembrane segments 3 and 4. The structural models suggested that hula twist is a primary process for the photoisomerization of the analog chromophores.
