New potent enkephalin analogs containing trifluoromethylamino acid residues

New potent enkephalin analogs containing trifluoromethylamino acid residues Replacement of the peptide-backbone amides connecting Tyr-Gly and Gly-Gly in leucine-enkephalin with ketomethylene groups: synthesis and biological activity Enkephalin analogues with 2′,6′-dimethylphenylalanine replacing phenylalanine in position 4 Novel analogs of enkephalin: identification of functional groups required for biological activity Design of enkephalin modifications protected from brain extracellular peptidases providing long-term analgesia New carboxyalkyl inhibitors of brain enkephalinase: synthesis, biological activity and analgesic properties Syntheses of potent Leu-enkephalin analogs possessing β-hydroxy-α,α-disubstituted-α-amino acid and their characterization to opioid receptors Synthesis and Biological Activities of Cyclic Lanthionine Enkephalin Analogues:  δ-Opioid Receptor Selective Ligands Preparation and analgesic properties of amino acid derivatives of (-)-5,9.alpha.-diethyl-2'-hydroxybenzomorphan Synthesis and structure-activity relationships of dynorphin A-(1-8) amide analogs