title: [Labeling of beta-endorphin and beta-lipotropin with iodine 125].
abstract: 5 micrograms of human beta-endorphin were labelled with 2 mCi 125I by the chloramine T technique. After two gel filtrations on Sephadex G-15 and on Sephadex G-50 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer was obtained with a specific activity about 150 microCi/ug. Kept at + 4 degrees C, the tracer remained utilizable for 30 days without loss of immunoreactivity. The labelling with lactoperoxydase and the use of another gel filtration method (filtration on Aca 202) gave a 125I beta-END tracer with the same immunoreactivity. The binding of this tracer to the antibody of an anti-beta-END antiserum diluted at 1/8000 was 32% with a non specific binding of 2%. 5 micrograms of human beta-lipotropin were labelled with 0.5 mCi 125I by the lactoperoxydase method. After two gel filtrations on Sephadex G-25 and on Sephadex G-75 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer with a specific activity of 140 microCi/micrograms was obtained. It remained utilizable for 30 days when kept at + 4 degrees C. Gel filtration on Aca 202 did not give good purification, while gel filtration on Aca 54 was good but slower than on Sephadex G-75. The binding to antibody in absence of unlabelled beta-LPH was 32% for an anti-beta-LPH antiserum diluted at 1/4000. The non specific binding was 2.5%.
mesh_terms: D004723:Endorphins; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods*; D001615:beta-Endorphin; D008083:beta-Lipotropin
chemical_list: D004723:Endorphins; D007457:Iodine Radioisotopes; D001615:beta-Endorphin; D008083:beta-Lipotropin
vernacular_title: Etude du marquage de la beta-endorphine (beta-END) et de la beta-lipotropine (beta-LPH) par l'iode 125.