title: Sulfonic acid enkephalin: binding specificity to rat brain opiate receptors.
abstract: We tested sulfonic-acid enkephalin, a SO3H-Tyr derivative of the Leu-enkephalin, for its binding capacity to rat brain opiate receptors, by competition against several tritiated enkephalins. Using [3H]DADLE as the competitor, we demonstrated that sulfonic-acid enkephalin binds to rat brain opiate receptors, and using [3H]DSLET and [3H]DAGO as the competitors, we demonstrated that sulfonic-acid enkephalin binds preferentially to delta-opiate receptors. The affinity ratio of sulfonic-acid enkephalin for delta-opiate receptors versus mu-opiate receptors, is considerably higher than that of the parent compound, Leu-enkephalin, and of DADLE and is similar to the affinity ratio of DSLET for the same receptors.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives* / Q000378:metabolism; D016308:Enkephalin, Leucine-2-Alanine; D004745:Enkephalins / Q000378:metabolism; D007700:Kinetics; D008297:Male; D009842:Oligopeptides / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D004745:Enkephalins; D009842:Oligopeptides; D011957:Receptors, Opioid; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-