title: Met-enkephalin-Arg6-Phe7, present in high amounts in brain of rat, cattle and man, is an opioid agonist.
abstract: The enkephalins Met-enkephalin and Leu-enkephalin were first isolated from porcine brain by Hughes and co-workers. We have recently isolated from bovine adrenals another enkephalin with the structure Tyr-Gly-Gly-Phe-Met-Arg-Phe, or Met-enkephalin-Arg6-Phe7 (ref. 2). We report here that this new heptapeptide is found in human, rat and bovine striatum in concentrations comparable with or greater than that of Leu-enkephalin. This molecule should not be considered as a mere precursor of Met-enkephalin. A pharmacological study indicates that this naturally occurring enkephalin has similar properties to the two enkephalins characterized earlier.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D001923:Brain Chemistry; D002417:Cattle; D003342:Corpus Striatum / Q000032:analysis*; D004723:Endorphins / Q000302:isolation & purification*; D004745:Enkephalins / Q000302:isolation & purification* / Q000494:pharmacology; D006801:Humans; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects*
chemical_list: D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid