title: Dehydro-enkephalins. III. Synthesis and biological activity of [delta Ala2, Leu5]-enkephalin.
abstract: [delta Ala2, Leu5]-enkephalin has been prepared and shown to be more active than the parent saturated enkephalin in a binding assay using rat brain membranes and [3H]dihydromorphine as a tracer. In a comparison of potencies against [3H]dihydromorphine and [3H]-[D-Ala2, D-Leu5]-enkephalin as tracers, [delta Ala2, Leu5]-enkephalin showed preference for micro opiate receptors, possibly due to the hydrophobicity of the delta Ala2 residue. A synthetic tetrapeptide enkephalin [delta Ala2]-desLeu5-enkephalin had weak activity and high selectivity for the micro receptors. O-Acylation of a serine residue in the peptide was achieved by coupling between the peptide and a carboxylic acid using DCC and a catalytic amount of 4-dimethylaminopyridine.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D004090:Dihydromorphine / Q000378:metabolism; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D016308:Enkephalin, Leucine-2-Alanine; D008722:Methods; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism
chemical_list: D011957:Receptors, Opioid; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D004090:Dihydromorphine