77265-43-1Relevant academic research and scientific papers
Preparation and photolysis of deuterium-labelled rhodopsin analogues
Fransen, M. R.,Palings, I.,Lugtenburg, J.,Jansen, P. A. A.,Groenendijk, G. W. T.
, p. 384 - 391 (2007/10/02)
The compounds 18- and 19-trideutero-11-cis-retinal, > 99percent pure, with over 98percent and 99percent trideuterium incorporation were synthesized together with the corresponding all-trans derivatives.Rhodopsins were prepared from bovine opsin and 18- and 19-trideutero-11-cis-retinal, 18- and 19-trideutero-all-trans-retinal were isolated as oximes after photolysis of the corresponding rhodopsins.The oximes showed the same deuterium incorporation as the starting 18- and 19-trideutero-11-cis-retinals and as those oximes obtained by denaturation of 18- and 19-trideuterorhodopsin in the dark.These results demonstrate that during rhodopsin photolysis no detectable exchange of D or H occurs at carbon atoms 18 and 19.These facts, together with Resonance Raman data of 18-trideutero-bathorhodopsin and 5-demethylbathorhodopsin, establish that the primary step in rhodopsin photochemistry is not a phototautomerization involving the 5-CH3 group.With respect to the possibility that the primary step is a phototautomerization involving the 9-CH3 group, the situation is less clear.At this time experimental evidence of the various research disciplines is insufficiently conclusive to establish unambiguously which of the two possibilities, cis-trans photoisomerization or phototautomerization involving the 9-CH3 group, is the primary event in visual photochemistry.
