Opioid activity of 4-imidazolidinone positional analogues of Leu-Enkephalin

Opioid activity of 4-imidazolidinone positional analogues of Leu-Enkephalin Synthesis and pharmacological characterization in vitro of cyclic enkephalin analogs: effect of conformational constraints on opiate receptor selectivity Replacement of the peptide-backbone amides connecting Tyr-Gly and Gly-Gly in leucine-enkephalin with ketomethylene groups: synthesis and biological activity Synthesis, opiate receptor affinity, and conformational parameters of [4-tryptophan]enkephalin analogs Syntheses of potent Leu-enkephalin analogs possessing β-hydroxy-α,α-disubstituted-α-amino acid and their characterization to opioid receptors Enkephalin analogues with 2′,6′-dimethylphenylalanine replacing phenylalanine in position 4 Synthesis and Biological Activities of Cyclic Lanthionine Enkephalin Analogues:  δ-Opioid Receptor Selective Ligands Systematic replacement of amides by 1,4-disubstituted[1,2,3]triazoles in Leu-enkephalin and the impact on the delta opioid receptor activity Synthesis and structure-activity relationships of dynorphin A-(1-8) amide analogs Peptides as receptor selectivity modulators of opiate pharmacophores