title: alpha-Neo-endorphin: receptor binding properties of the tritiated ligand.
abstract: Tritiated porcine alpha-neo-endorphin has been prepared from its corresponding iodinated analog. The iodinated analog (diiodotyrosine at position 1) was synthesized, along with its non-iodinated counterpart, by the solid-phase method. Catalytic exchange of this iodinated analog in the presence of tritium yielded tritiated porcine alpha-neo-endorphin having a specific activity of 45.5 Ci/mmole. Both the native, iodinated and tritiated alpha-neo-endorphin analogs were shown to be homogenous by chromatography on carboxymethylcellulose, paper chromatography, paper electrophoresis, high performance liquid chromatography and amino acid analysis. For the first time binding of alpha-neo-endorphin to rat membrane preparations is described using [3H2-Tyr1]alpha-neo-endorphin as the ligand. The binding is time-dependent and saturable with respect to alpha-neo-endorphin. Scatchard analysis was bi-phasic with KDs of 0.20 and 3.75 nM. Displacement binding studies indicate that the receptor for alpha-neo-endorphin has "kappa" and possibly "epsilon" binding characteristics.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism*; D014316:Tritium
chemical_list: D004723:Endorphins; D011498:Protein Precursors; D011957:Receptors, Opioid; D014316:Tritium; C025681:alpha-neoendorphin