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Endothelin 1 hydrolysis by rat kidney membranes
Author(s) -
Yamaguchi Toru,
Fukase Masaaki,
Arao Makoto,
Sugimoto Toshitsugu,
Chihara Kazuo
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80794-h
Subject(s) - phosphoramidon , neprilysin , endopeptidase , chemistry , endothelin receptor , hydrolysis , cleavage (geology) , biochemistry , enzyme , kidney , chromatography , biology , endocrinology , receptor , paleontology , fracture (geology)
Hydrolysis of endothelin 1 by rat kidney membranes was investigated using a reverse‐phase HPLC and an automated gas‐phase protein sequencer. Endothelin 1 was hydrolyzed into four major fragments which were detected by HPLC, Phosphoramidon, an inhibitor of neutral endopeptidase 24,11, almost completely suppressed the production of three fragments, but one fragment was not affected by the inhibitor. Analysis of N‐terminal sequences of the degradation products revealed that the phosphoramidon‐sensitive fragments were generated by cleavage at the Ser 5 –Leu 6 bond of endothelin 1 that was identical with its cleavage site by purified rat endopeptidase 24,11, reported previously. The phosphoramidon‐insensitive fragment was produced by cleavage at Leu 17 –Asp 18 , which was distinct from the sites by endopeptidase 24,11, but corresponded to that by a phosphoramidon‐insensitive metallo‐endopeptidase recently isolated from rat kidney membranes by μs [(1992) Eur. J. Biochem. 204, 547–552]. Kinetic determination of endothelin 1 hydrolysis by the isolated enzyme yielded values of K m =71.5 μM and k cal =1.49 s −1 , giving a ratio of k cal K m =2.08 × 10 4 s −1 ·M −1 . The K m value was much higher and the k cal /K m value was much lower than those for rat endopeptidase 24,11 reported previously. Thus, endopeptidase 24,11 appears to hydrolyze endothelin 1 more efficiently than the isolated enzyme does. Both enzymes may play physiological roles in the metabolism of endothelin 1 by rat kidney membranes in vivo.