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 188.8.131.52) 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 μM) but not by thiorphan (10 μM). 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.
|Number of pages||4|
|Journal||Journal of Cardiovascular Pharmacology|
|Issue number||SUPPL. 8|
|Publication status||Published - 1993|
|Event||3rd International Conference on Endothelain - Houston, United States|
Duration: 15 Feb 1993 → 17 Feb 1993
Conference number: 3