4 SYNTHESIS AND PHOTOCHEMICAL REACTION OF 9-CIS-RETRO-γ-RHODOPSIN
Details
Retro-γ-retinal, possessing the dissected diene and trienal groups, has been investigated as a new chromophore in rhodopsin analogues. The syntheses and spectral properties of the three retro-γ-retinal isomers [all-trans(VIIa), 11-cis(VIIa') and 9-cis(VIIb)] have been described. Of these three isomers, (VIIb) has given a new artificial visual pigment, 9-cis-retro-γ-rhodopsin (VIIIb)[λ_<max>=420 nm]. From the results of the photochemical reaction of (VIIIb) at a liquid nitrogen temperature, it has been infered that the formation of bathorhodopsin is due to the photoisomerization of the chromophore in the rhodopsin molecule and is not attributed to the translocation of a proton from C-4〜C-8 to the Schiff-base nitrogen in the retinylidene chromophore.
