title: Morphine-like peptides in mammalian brain: isolation, structure elucidation, and interactions with the opiate receptor.
abstract: A substance that competes for opiate receptor binding has been isolated from calf brain and identified as two pentapeptides, H-Tyr-Gly-Gly-Phe-Met-OH (methionine enkephalin) and H-Tyr-Gly-Gly-Phe-Leu-OH (leucine enkephalin), with about four times more leucine enkephalin than methionine enkephalin. Sodium and manganese effects on opiate receptor interactions show that both peptides are agonists, whereas leucine enkephalin may be a "purer" agonist than methionine enkephalin.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001667:Binding, Competitive; D001923:Brain Chemistry; D002417:Cattle; D008024:Ligands; D008345:Manganese / Q000494:pharmacology; D009270:Naloxone / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000302:isolation & purification*; D009842:Oligopeptides / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D011955:Receptors, Drug / Q000187:drug effects; D012964:Sodium / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D008024:Ligands; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D011955:Receptors, Drug; D009270:Naloxone; D008345:Manganese; D012964:Sodium