Carbohydrate composition of bovine rhodopsin.
The carbohydrate content of bovine rhodopsin was investigated and found to be different from previously reported values. Rod outer segments were isolated from dark-adapted bovine retinas by sucrose flotation and purified by sucrose density contrifugation. Rhodopsin was extracted with detergents and purified by chromatographic procedures involving calcium phosphate/celite chromatography followed by affinity chromatograpy on concanavalin A-Sepharose (or in some cases, gel filtration on agarose). Purified preparations of rhodopsin had A278/A498 ratios of 1.6 to 2.0. After treatment of the rhodopsin with chloroform/methanol (2/1) to remove lipids and detergents, the carbohydrate content was measured by gas-liquid chromatography, colorimetric and enzymatic analyses, paper chromatography, and electrophoresis. Rhodopsin was found to have about 9 mol of mannose and 5 mol of glucosamine per mol of visual pigment. A molar ratio of mannose/glucosamine of about 2 was also found in samples of rhodopsin obtained from two other laboratories. The amino acid analysis was similar to previously published values.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D003624:Darkness; D008027:Light; D008358:Mannose / Q000032:analysis; D010786:Photoreceptor Cells / Q000032:analysis; D012168:Retinal Pigments / Q000302:isolation & purification; D012243:Rhodopsin / Q000302:isolation & purification; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet
D000596:Amino Acids; D012168:Retinal Pigments; D012243:Rhodopsin; D008358:Mannose