title: beta-Lipotropin as a prohormone for the morphinomimetic peptides endorphins and enkephalins.
abstract: The hypophysial homomeric peptide beta-lipotropin (beta-LPH-[1-91]) has no morphinomomimetic activity in a bioassay (myenteric plexus-longitudinal muscle of the guinea pig's ileum) or binding assays with stereospecific opiate-receptors of rat brain synaptosome preparations. Incubating beta-LPH-[1-91] at neutral pH with the supernatant aqueous extracts of rat brain generates (fragments of beta-LPH with) morphinomimetic activity in the same assay systems. These results are related to the recently recognized structural relationships between beta-LPH, the newly isolated peptides met-enkephalin (beta-LPH-[61-65]) and alpha-endorphin (beta-LPH-[61-76]) and also to the biologically active fragments of analogs: beta-LPH-[61-64], beta-LPH-[61-65[-NH2, (Met(O)65)-BETA-LPH-[61-65], beta-LPH-[61-69], and beta-LPH-[61-69]. Enzymatic biogenesis of these morphinomimetic peptides would preclude localizing them as such in cellular or subcellular elements with currently available methodology.
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D005048:Etorphine / Q000378:metabolism; D007082:Ileum / Q000187:drug effects; D009022:Morphine Derivatives / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000378:metabolism; D009842:Oligopeptides / Q000096:biosynthesis* / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011955:Receptors, Drug; D013329:Structure-Activity Relationship; D008083:beta-Lipotropin / Q000378:metabolism*
chemical_list: D009022:Morphine Derivatives; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D011498:Protein Precursors; D011955:Receptors, Drug; D009270:Naloxone; D005048:Etorphine; D008083:beta-Lipotropin