title: Characterisation of N-terminally extended met-enkephalin Arg6Gly7Leu8 variants in the porcine upper digestive tract.
abstract: Proenkephalin A-derived peptides are known to occur in the gut, but their precise identity is uncertain. We report here the isolation of N-terminally extended forms of Met-enkephalin Arg6Gly7Leu8 from porcine upper digestive tract monitored by radioimmunoassay. A single major form was identified in pyloric antral muscle and mucosa, but in the duodenum two major forms were detected. Microsequence analysis together with immunological data revealed that the antral mucosal peptide and the most acidic duodenal peptide had identical amino-acid sequences, corresponding to a 5.3 kDa peptide terminating in Met-enkephalin Arg6Gly7Leu8. The data indicate that high-molecular-weight peptides may constitute a major proportion of gut opioid peptide immunoactivity.
authors.affiliation: Physiological Laboratory, University of Liverpool, U.K.
authors.forename: A
authors.initials: A
authors.lastname: Watkinson
authors.forename: G J
authors.initials: GJ
authors.lastname: Dockray
authors.forename: J
authors.initials: J
authors.lastname: Young
authors.forename: H
authors.initials: H
authors.lastname: Gregory
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004386:Duodenum / Q000032:analysis*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000032:analysis; D004745:Enkephalins / Q000032:analysis; D011498:Protein Precursors / Q000032:analysis; D011706:Pyloric Antrum / Q000032:analysis; D011708:Pylorus / Q000032:analysis; D013270:Stomach / Q000032:analysis*; D013552:Swine
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; C029992:proenkephalin; D004744:Enkephalin, Methionine; C033453:enkephalin-Met, Arg(6)-Gly(7)-Leu(8)-