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      Digestion and assimilation of proline-containing peptides by rat intestinal brush border membrane carboxypeptidases. Role of the combined action of angiotensin-converting enzyme and carboxypeptidase P.

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          Abstract

          Two intestinal brush border membrane carboxypeptidases were found to participate in the sequential digestion of proline-containing peptides representing a novel mechanism of hydrolysis from the COOH terminus. NH2-blocked prolyl tripeptides were rapidly hydrolyzed by either brush border membrane angiotensin converting enzyme (ACE, dipeptidyl carboxypeptidase, E.C. 3.4.15.1) or carboxypeptidase P (E.C.3.4.12-) depending on the position of the proline residue. Furthermore, these two enzymes were found to participate in a concerted manner to sequentially degrade larger proline-containing pentapeptides from the COOH terminus. A brush border membrane associated neutral endopeptidase also participated in the hydrolysis of the prolyl pentapeptides. During in vivo intestinal perfusion, the NH2-blocked prolyl peptides were degraded and their constituent amino acids efficiently absorbed by the intestine. Furthermore, hydrolysis and absorption of these peptides could be dramatically suppressed by low concentrations of captopril, a specific inhibitor of ACE. These studies show that prolyl peptides are efficiently and sequentially hydrolyzed from the COOH terminus by the combined action of ACE and carboxypeptidase P, and that these enzymes may play an important role in the digestion and assimilation of proline-containing peptides.

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          Author and article information

          Journal
          J. Clin. Invest.
          The Journal of clinical investigation
          American Society for Clinical Investigation
          0021-9738
          0021-9738
          Apr 1988
          : 81
          : 4
          Affiliations
          [1 ] Gastrointestinal Research Laboratory, Veterans Administration Medical Center, San Francisco, California 94121.
          Article
          10.1172/JCI113421
          329635
          2832443
          92ab5161-38bf-42e8-92c2-e811d2580c81
          History

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