APPLICATION OF ARTIFICIAL PIGMENTS TO STRUCTURE DETERMINATION AND STUDY OF PHOTOINDUCED TRANSFORMATIONS OF RETINAL PROTEINS

The protonated Schiff bases of all-trans-retinal and its double bond i somers, 11-cis- and 15-cis-retinals, comprise the chromophores of bact eriorhodopsin, sensory rhodopsin, rhodopsin, and the Chlamydomonas pho toreceptor pigment. Absorption of photons by these chromophores is dir ectly responsible for the functioning of the various photopigments. Cl arification of their extremely complex structures and mechanisms requi res multidisciplinary collaboration. The study of synthetic retinal an alogs and pigments reconstituted from analogs provides a powerful and indispensable tool for such clarification. This article summarizes the application of retinal analogs in the bioorganic, biophysical, and bi ochemical investigations of the various retinal pigments.