Phosphoramidon-sensitive endothelin converting enzyme in rat lung.
A neutral proteinase with endothelin (ET)-1 converting activity was identified in cytosol and membrane fractions prepared from rat lung, in a ratio of 1:4, respectively. The membrane-bound proteinase was solubilized by 0.5% 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) with an increase in specific activity, and then was characterized. The solubilized proteinase was capable of converting big ET-1 to ET-1 with an optimum pH of 6.5, and the conversion was dose-dependently suppressed by phosphoramidon (IC50 = 0.5 microM). The molecular mass of the proteinase was estimated to be about 500 kDa by gel filtration in the presence of 0.5% CHAPS. These results indicate that rat lung contains a phosphoramidon-sensitive neutral proteinase catalyzing conversion of big ET-1 to ET-1. The proteinase may be involved in the biosynthetic pathway of ET-1 in the lung and/or the conversion of circulating big ET-1.
Takaoka
M
M
Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
Shiragami
K
K
Fujino
K
K
Miki
K
K
Miyake
Y
Y
Yasuda
M
M
Wang
G F
GF
Hisaki
K
K
Matsumura
Y
Y
Morimoto
S
S
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D002793:Cholic Acids; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins; D006020:Glycopeptides / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008168:Lung / Q000201:enzymology*; D008297:Male; D008566:Membranes / Q000201:enzymology; D008666:Metalloendopeptidases; D008970:Molecular Weight; D051381:Rats; D012995:Solubility
D002793:Cholic Acids; D016232:Endothelins; D006020:Glycopeptides; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D000072396:Endothelin-Converting Enzymes; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate; C008890:phosphoramidon