title: Processing and metabolism of endothelin peptides by porcine lung membranes.
abstract: The processing and metabolism of big endothelin-1 (big ET-1) and endothelin-1 (ET-1) by a membrane fraction from pig lung was examined. The principal activity in this membrane fraction hydrolyzing ET-1 was identified as endopeptidase-24.11 (EC 3.4.24.11) by inhibitory and immunological criteria. More than 90% of this endopeptidase-24.11 activity could be removed by immunoadsorption. ET-converting activity was partially purified from the solubilized membrane fraction by lectin chromatography on a Ricinus communis agglutinin-120-agarose column followed by immunodepletion of endopeptidase-24.11. The production of the C-terminal fragment of big ET-1 could be detected in this partially purified preparation and was inhibited by phosphoramidon (10 microM) but not by thiorphan (10 microM). The fluorogenic substrate succinyl-Ile-Ile-Trp-7-amido-4-methylcoumarin was hydrolyzed by pig lung membranes, but this activity was insensitive to phosphoramidon, suggesting that neither endopeptidase-24.11 nor endothelin-converting enzyme hydrolyze this substrate. Purified endopeptidase-24.11 also failed to hydrolyze the fluorogenic peptide.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Leeds, England.
authors.forename: L J
authors.initials: LJ
authors.lastname: Murphy
authors.forename: K J
authors.initials: KJ
authors.lastname: Greenhough
authors.forename: A J
authors.initials: AJ
authors.lastname: Turner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins / Q000378:metabolism*; D037102:Lectins; D008168:Lung / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008566:Membranes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008666:Metalloendopeptidases; D008969:Molecular Sequence Data; D015260:Neprilysin / Q000378:metabolism; D037121:Plant Lectins; D011480:Protease Inhibitors / Q000494:pharmacology; D013552:Swine
chemical_list: D016232:Endothelins; D037102:Lectins; D037121:Plant Lectins; D011480:Protease Inhibitors; C017707:Ricinus communis agglutinin-1; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D015260:Neprilysin; D000072396:Endothelin-Converting Enzymes