title: Morphine-like activity of sheep beta-lipotropin and of its tryptic fragments.
abstract: Sheep beta-lipotropin (beta-LPH) (sequence 1-91) was selectively cleaved with trypsin after blocking the epsilon-amino groups of lysine with citraconic anhydride. The resulting peptides were purified by a combination of cation-exchange chromatography and high-voltage electrophoresis. The purified fragments were then tested for their morphine-like activity in the mouse vas deferens bioassay. The active peptides were 61-91 and 61-80 were about as active as the synthetic methionine-enkephalin, and in turn these were about 100 times more active than beta-LPH itself. The inhibition of electrically stimulated mouse vas deferens by these peptides is reversed by naloxone, and suggests a competitive character of interaction. It is thus concluded that the active core for the morphine like activity in the mouse vas deferens bioassay is the fragment 61-65 of beta-LPH.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D008297:Male; D051379:Mice; D009020:Morphine; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D012756:Sheep; D014357:Trypsin; D014649:Vas Deferens / Q000187:drug effects; D008083:beta-Lipotropin / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D010455:Peptides; D009020:Morphine; D008083:beta-Lipotropin; D014357:Trypsin