- Synthesis and spectroscopic characterization of the doubly locked 9E,11Z retinal model systems 7E,13E-11,19-10,29-dimethanoretinal and its 13Z isomer
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7E,13E-11,19-10,20-dimethanoretinal (1) and its 13Z isomer 2 were prepared from β-ionone, using the novel synthon 2-(diethoxyphosphinyl)-5,5-dimethoxyhexanenitrile.This synthon was also used to prepare 7E,9E,13E-10,20-methanoretinal (3) and its 13Z isomer 4 in high yield, starting from β-ionone.Spectroscopic analysis (mass, 1H and 13C NMR and UV/Vis) of these compounds is discussed.The introduction of the methano bridges leads to minimal steric and electronic changes.The photostationary state reached from 1 and 2 has the 13Z form 2 as the main constituent.This is one of the very few with a Z form as the main constituent of the photostationary state. 1 and 2 are very sensitive to acid-catalyzed isomerization of the 13-C=14-C double bond.The presence of the 11,19-methano bridge is responsible for this efficient Z-E isomerization.
- Groesbeek, M.,Robijn, G. W.,Lugtenburg, J.
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- All E-10,20-methanoretinoylopsin, light-stable rhodopsin. Synthesis and spectroscopy of all E-10,20-methano- and all-E-retinoyl fluoride and their reaction with bovine opsin
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In order to obtain a light-stable rhodopsin as a potential candidate for crystallization and structural X-ray analysis, we synthesized and characterized the novel all E-10,20-methanoretinoyl fluoride (2).This retinal analogue has a locked 11-cis configuration, preventing the light-induced 11-cis -> trans isomerization and binds to opsin by a stable peptide bond rather than a Schiff base. 2 reacted with (methylated) bovine opsin, forming a light- and thermo-stable pigment with λmax at 390 nm.Its opsin shift (2500 cm-1) is in the same order of magnitude as that in rhodopsin (2650 cm-1), suggesting that the mechanism for the red shift is not located in the direct vicinity of the chromophore-protein linkage.We also report the first synthesis and characterization of all-E-retinoyl fluoride (10), which failed to give a pigment on reaction with bovine opsin.
- Steen, R. van der,Groesbeek, M.,Amsterdam, L. J. P. van,Lugtenburg, J.,Oostrum, J. van,Grip, W. J. de
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