title: Selective labelling of apolipoproteins A-I and C-I at methionine residues by (3H) methyl exchange.
abstract: Apolipoproteins C-I and A-I were radioactively labelled with tritium by (3H)-methyl exchange. The methionine residues were first methylated with (3H)-methyl iodide at pH 4 and the reaction products were purified by gel filtration and cation exchange chromatography. The products were then demethylated with 2-mercaptoethanol (6 M) at pH 8.6 to regenerate the apolipoproteins in an unmodified but tritiated form. The specific radioactivity for apolipoprotein C-I and A-I was 3.5 X 10(6) and 1.5 X 10(7) dpm/pmol respectively. The properties of (3H)-apolipoprotein C-I were examined by reversed phase HPLC and by incorporation into very low density lipoproteins (VLDL).
mesh_terms: D016632:Apolipoprotein A-I; D053302:Apolipoprotein C-I; D001054:Apolipoproteins A / Q000097:blood; D001056:Apolipoproteins C / Q000097:blood; D002848:Chromatography, DEAE-Cellulose; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006847:Hydrocarbons, Iodinated; D007553:Isotope Labeling / Q000379:methods; D008075:Lipoproteins, HDL / Q000097:blood; D014316:Tritium
chemical_list: D016632:Apolipoprotein A-I; D053302:Apolipoprotein C-I; D001054:Apolipoproteins A; D001056:Apolipoproteins C; D006847:Hydrocarbons, Iodinated; D008075:Lipoproteins, HDL; D014316:Tritium; C014055:methyl iodide