Phosphoramidon-sensitive endothelin-converting enzyme in the cytosol of cultured bovine endothelial cells.
Neutral metalloproteases with endothelin-1 (ET-1) converting activity were detected in membranous and cytosolic fractions of cultured endothelial cells (EC) from bovine carotid artery in a ratio of 5:1, respectively. The cytosolic enzyme specifically and quantitatively converts big ET-1 to ET-1 (Km = 10.7 microM), but does not convert big ET-3. Like the membranous enzyme, the cytosolic enzyme is only active at pH 6.5-7.5, and is competitively inhibited by phosphoramidon (Ki = 0.79 microM). The apparent molecular weight of the cytosolic enzyme is about 540 kD, which is 5-6 times greater than that of the membranous enzyme. These results indicate the presence of two types of phosphoramidon-sensitive neutral ET-converting enzyme in vascular EC.
Takada
J
J
Central Research Laboratories, Banyu Pharmaceutical Co., Ltd., Tokyo, Japan.
Okada
K
K
Ikenaga
T
T
Matsuyama
K
K
Yano
M
M
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002850:Chromatography, Gel; D003600:Cytosol / Q000378:metabolism; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D006020:Glycopeptides / Q000494:pharmacology*; D007700:Kinetics; D008666:Metalloendopeptidases; D008970:Molecular Weight
D016232:Endothelins; D006020:Glycopeptides; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D000072396:Endothelin-Converting Enzymes; C008890:phosphoramidon