PREPARATION AND PROPERTIES OF NEW VISUAL PIGMENT ANALOGUES FROM 5,6-DIHYDRORETINAL AND CATTLE OPSIN*

Abstract— On irradiation of all-trans 5,6-dihydroretinal (I), two opsin-active isomers are formed. Both these isomers (believed to be the 11-cis and 9-cis isomers) individually couple with cattle opsin to form complexes which have maximal absorption at 465 nm. These complexes satisfy all the established criteria characteristic of synthetic visual pigments.