title: The 3, 4-didehydroretinal chromophore of goldfish porphyropsin.
abstract: The isomeric configuration of the 3,4-didehydroretinal chromophore of goldfish porphyropsin was determined by high performance liquid chromatography (HPLC) and by the regeneration of this visual pigment with authentic isomers of 3,4-didehydroretinal. A nonisomerizing, quantitative method using hydroxylamine and methylene chloride was employed to extract the 3,4-didehyroretinal chromophore from the rod outer segment membrane (containing the porphyropsin). When this extracted chromophore was injected into the HPLC, only a single major peak was observed and this peak coeluted with the authentic 11-cis 3,4-didehydroretinyl oxime. This suggests that the chromophore of goldfish porphyropsin is 11-cis 3,4-didehydroretinal. When the bleached rod outer segments (containing the opsin) were incubated with different 3,4-didehydroretinal isomers (13-cis, 11-cis, 9-cis, and all-trans), only the 11-cis isomer resulted in the degeneration of porphyropsin. This also suggests that the porphyropsin chromophore exists in the 11-cis configuration.
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006054:Goldfish; D007536:Isomerism; D010786:Photoreceptor Cells / Q000032:analysis*; D012168:Retinal Pigments / Q000302:isolation & purification*; D012374:Rod Cell Outer Segment / Q000032:analysis*; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
chemical_list: D012168:Retinal Pigments; C010507:porphyropsin