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Isolation of a neuropeptide-degrading carboxypeptidase from the human stomach.

Authors
  • 1
  • 1 Department of Surgery, University of California, San Francisco.
Type
Published Article
Journal
Gastroenterology
0016-5085
Publisher
Elsevier
Publication Date
Volume
102
Issue
1
Pages
76–87
Identifiers
PMID: 1309362
Source
Medline
License
Unknown

Abstract

The aim of this investigation was to isolate and characterize a neuropeptide-degrading carboxypeptidase from the muscular and mucosal layers of the human stomach. The carboxypeptidase was solubilized from membrane preparations of gastric muscle and mucosa using Triton X-100. The detergent-solubilized enzyme was purified to apparent electrophoretic homogeneity by affinity chromatography using lisinopril or potato carboxypeptidase inhibitor as an affinity ligand. The enzyme had an apparent molecular weight of 34,300 and was bound by concanavalin A and is thus a glycoprotein. The carboxypeptidase removed C-terminal leucine, phenylalanine, or tryosine residues from peptides including angiotensin I, [Leu5]enkephalin, kinetensin, neuromedin N, neurotensin, and xenopsin. It had an alkaline pH optimum and was inhibited by lisinopril, potato carboxypeptidase inhibitor, ethylenediaminetetraacetic acid, 1,10-phenanthroline, and 8-hydroxyquinoline. Immunoblotting indicated that the gastric carboxypeptidase cross-reacted with an antibody raised against a carboxypeptidase isolated from mast cells of human skin. The gastric carboxypeptidase released from gastric mast cells upon degranulation may act to degrade and inactivate neuropeptides in the stomach wall.

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