title: Reductively methylated, tritiated rhodopsin of high specific activity; a convenient sensitive tracer for use in the radioimmunoassay of rhodopsin.
abstract: Bovine rhodopsin was subjected to reductive methylation in the dark using formaldehyde and high specific activity sodium borotritide. After purification by gel filtration and affinity chromatography on Concanavalin A-Sepharose, the product retained its immunoreactive properties. [3H]-Reductively methylated rhodopsin (specific activity, 32 Ci/mmole) was suitable for use in radioimmunoassays for rhodopsin, having many advantages over radioiodinated rhodopsin for this purpose. The site of the reductive methylation was shown to be the non-active site lysines with the production of tritiated N-epsilon-dimethyllysine and tritiated N-epsilon-methyllysine in a molar ratio of about 1.3:1, respectively. In terms of stability, ease of preparation, and specificity, tritiated, reductively methylated rhodopsin presents itself as a preferable ligand to radioiodinated rhodopsin in many applications, such as the radioimmunoassay.
authors.affiliation: Department of Ophthalmology, Case Western Reserve University, Cleveland, OH.
authors.forename: A V
authors.initials: AV
authors.lastname: Prasad
authors.forename: J M
authors.initials: JM
authors.lastname: Ju
authors.forename: J J
authors.initials: JJ
authors.lastname: Plantner
authors.forename: E L
authors.initials: EL
authors.lastname: Kean
mesh_terms: D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D008024:Ligands; D008745:Methylation; D010084:Oxidation-Reduction; D011863:Radioimmunoassay / Q000379:methods*; D012243:Rhodopsin / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D013053:Spectrophotometry; D014316:Tritium
chemical_list: D008024:Ligands; D014316:Tritium; D012243:Rhodopsin