Retinal analogues

It is an important experimental advantage that the halobacterial photoreceptor apoproteins (so-called sensory opsins, SO) are expressed by the cell even in absence of retinal. Retinal biosynthesis can be blocked either genetically or simply by addition of nicotine to a growing culture. Upon addition of external retinal, active photoreceptors spontaneously reconstitute in vivo. This kind of experiment showed that photoreception is strictly retinal-dependent. By incorporation of artificially synthesized retinal analogues into sensory opsins, John Spudich and coworkers obtained valuable information on the activation process of the sensory rhodopsins. 

There are many synthetically useful conversion reactions of a,p-unsaturated nitriles to a,p-unsaturated aldehydes using DIBAL-H. To illustrate the value of the method, we have brought together all the examples concerned with chemistry of retinal. Thus, the applicability of the sequence combining the use of diethyl cyanomethylphosphonate with diethyl 3-cyano-2-methyl-2-prope-nylphosphonate, diethyl 3-cyano-2-butenylphosphonate, or diethyl 3-cyano-2-methyl-l-ethyl-2-propenylphosphonate has been studied intensively in retinal synthesis to prepare retinal analogues ... 

Ito, M., Kodama, A., Hiroshima, T., and Tsukida, K., Retinoids and related compounds. Part 9. Synthesis and spectral characteristics of retinal analogues involving the ll- s-locked-cyclopentatrie-nyhdene structure, 7. Chem. Soc., Perkin Trans. 1, 905, 1986. 

Intramolecular heavy atom effects influence the photoisomerization derivatives of 5,5-diphenyl-1,3-cyclohexadiene The homogeneous acid catalysis of the photoisomerization of trans-3-(2-hydroxy-benzylidene)-4,5-dihydrofuran-2(3H)-one and model mechanisms for isomerization of carbocyanines have both been analyzed. The process of photoisomerization of the biologically important rhodopsin and bacteriorhodopsin has been examined by a theoretical ab initio study of retinal analogues. ... 

Details of the resonance Raman spectra of retinal and retinal analogues, and of visual pigments" " and bacteriorhodopsin" " derived from them have been presented and analysed. 

Photoreceptor Pigments. Several aspects of the spectroscopy and photochemistry of the retinal-containing visual pigments have been reviewed/ Many papers report various aspects of the spectroscopy of retinal, retinal analogues, and Schiff s bases derived from them, and of rhodopsin and other intermediates in the visual pigment cycle. 124.126,127.144,170—187 studies on bacteriorhodopsin, the... 

The photoisomerization of retinal has been studied using super-short light pulses, and the neutral and protonated forms of the retinal analogue (47) have been examined by time-resolved methods.The irradiation of 3-ionone as a complex with P-CD in water leads only to the formation of retro-y-ionone." ... 

Many retinal and retinoic acid analogues have been synthesized. Many of the seven aromatic analogues of retinal (97)—(101), (103), and (104) and their geometrical isomers form stable complexes with cattle opsin, as does the allenic adamantyl retinal analogue (105) synthesized from adamantan-2-one. 5,6-Dihydro-, 7,8-dihydro, 9,10-dihydro-, 11,12-dihydro, and 9,10,11,12-tetra-hydro-retinals (106)—(110) have been synthesized from carbonyl intermediates, e.g. (Ill) prepared by selective reduction of the a,jS-unsaturation with... 

Figure 1. Structures of retinal and retinal analogues. 1. ll-cis retinal 2. ll-cis 3,4-dehydroretinal 3. l -cis 3-hydroxyretinal 4. ll-cis 4-hydroxyretinal 5. ll-cis 9-desmethylretinal...

The constraints of the binding site of rod rhodopsin have been extensively studied using retinal analogues [7] and from these studies the following generalizations can be made (Fig. 3) ... 

The development of the use of retinal analogues with isolated photoreceptors for physiological studies has proven to be a convenient tool for the comparison of rods and cones. A fundamental difference has been observed in the interaction of the retinal analogue p-ionone, which contains a truncated polyene chain (Fig. 5). In cones, it was determined that this analogue acts as... 

Okada, X, Kandori, H., Shichida, Y., Yoshizawa, X., Denny, M., Zhang, B.W., Asato, A.E., and Liu, R.S., Spectroscopic study of the batho-to-lumi transition during the photobleaching of rhodopsin using ring-modified retinal analogues. Biochemistry, 30,4796, 1991. 

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