ABSTRACT
It is generally accepted that vitamin A is particularly important for the promotion of general growth, the maintenance of visual function, the regulation of proliferation and differentiation of epithelial tissues, and reproduction. The mode of action of retinol and retinal in the visual cycle was elucidated by Wald. The visual pigment rhodopsin has been shown to contain 11-cis-retinal which is bound via a protonated Schiff-base linkage to the e-amino group of a specific lysyl residue of the apoprotein opsin. In order to clarify the primary photochemical event by chemical methods, two types of rhodopsin analogs were synthesized. The former was derived from 9-cis-retro--y-retinal having two dissected chromophoric systems, namely, one diene and one trienal chromophore. The latter was prepared from an 11-cis-locked-cyclopentatrienylidene retinal analog. The clarification of the origin of the induced circular dichroism of rhodopsin would be of particular interest for the conformational analysis of the photobleaching intermediates of rhodopsin.
