Neurotensin-Metabolizing Peptidases in Rat Fundus Plasma Membranes |
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Authors: | Frédéric Checler Hélène Barelli Chiu-Yin Kwan Patrick Kitabgi Jean-Pierre Vincent |
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Institution: | Centre de Biochimie, Facultédes Sciences, Universitéde Nice, Nice, France;Department of Neurosciences, McMaster University, Hamilton, Ontario, Canada |
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Abstract: | The mechanisms by which neurotensin (NT) was inactivated by rat fundus plasma membranes were characterized. Primary inactivating cleavages occurred at the Arg8-Arg9, Pro10-Tyr11, and Ile12-Leu13 peptidyl bonds. Hydrolysis at the Arg8-Arg9 bond was fully abolished by the use of N-1(R,S)-carboxy-2-phenylethyl]-alanyl-alanyl-phenylalanine-p- aminobenzoate, a result indicating the involvement at this site of a recently purified soluble metallopeptidase. Hydrolysis of the Pro10-Tyr11 bond was totally resistant to N-benzyloxycarbonyl-prolyl-prolinal and thiorphan, an observation suggesting that the peptidase responsible for this cleavage was different from proline endopeptidase and endopeptidase 24.11 and might correspond to a NT-degrading neutral metallopeptidase recently isolated from rat brain synaptic membranes. The enzyme acting at the Ile12-Leu13 bond has not yet been identified. Secondary cleavages occurring on NT degradation products were mainly generated by bestatin-sensitive aminopeptidases and post-proline dipeptidyl aminopeptidase. The content in NT-metabolizing peptidases present in rat fundus plasma membranes is compared with that previously established for purified rat brain synaptic membranes. |
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Keywords: | Neurotensin inactivation Rat fundus plasma membranes Neurotensin-degrading neutral metallopeptidase Rat brain soluble metallopeptidase |
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