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. 1994 Mar 15;298(Pt 3):635–639. doi: 10.1042/bj2980635

Metabolism of aspartame by human and pig intestinal microvillar peptidases.

N M Hooper 1, R J Hesp 1, S Tieku 1
PMCID: PMC1137907  PMID: 8141778

Abstract

The artificial sweetener aspartame (N-L-alpha-aspartyl-L-phenyl-alanine-1-methyl ester; Nutrasweet), its decomposition product alpha Asp-Phe and the related peptide alpha Asp-PheNH2 were rapidly hydrolysed by microvillar membranes prepared from human duodenum, jejunum and ileum, and from pig duodenum and kidney. The metabolism of aspartame by the human and pig intestinal microvillar membrane preparations was inhibited significantly (> 78%) by amastatin or 1,10-phenanthroline, and partially (> 38%) by actinonin or bestatin, and was activated 2.9-4.5-fold by CaCl2. The inhibition by amastatin and 1,10-phenanthroline, and the activation by CaCl2 are characteristic of the cell-surface ectoenzyme aminopeptidase A (EC 3.4.11.7) and a purified preparation of this enzyme hydrolysed aspartame with a Km of 0.25 mM and a Vmax of 126 mumol/min per mg. A purified preparation of aminopeptidase W (EC 3.4.11.16) also hydrolysed aspartame but with a Km of 4.96 mM and a Vmax of 110 mumol/min per mg. However, rentiapril, an inhibitor of aminopeptidase W, caused only slight inhibition (maximally 19%) of the hydrolysis of aspartame by the microvillar membrane preparations. Similar patterns of inhibition and kinetic parameters were observed for alpha Asp-Phe and alpha Asp-PheNH2. Two other decomposition products of aspartame, beta Asp-PheMe and cyclo-Asp-Phe, were essentially resistant to hydrolysis by both the human and pig intestinal microvillar membrane preparations and the purified preparations of aminopeptidases A and W. Although the relatively selective inhibitor of aminopeptidase N (EC 3.4.11.2), actinonin, partially inhibited the metabolism of aspartame, alpha Asp-Phe and alpha Asp-PheNH2 by the human and pig intestinal microvillar membrane preparations, these peptides were not hydrolysed by a purified preparation of aminopeptidase N. Membrane dipeptidase (EC 3.4.13.19) only hydrolysed the unblocked dipeptide, alpha Asp-Phe, but the selective inhibitor of this enzyme, cilastatin, did not block the metabolism of alpha Asp-Phe by the microvillar membrane preparations.

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Selected References

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  1. Booth A. G., Kenny A. J. A rapid method for the preparation of microvilli from rabbit kidney. Biochem J. 1974 Sep;142(3):575–581. doi: 10.1042/bj1420575. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bowes M. A., Kenny A. J. An immunohistochemical study of endopeptidase-24.11 and aminopeptidase N in lymphoid tissues. Immunology. 1987 Feb;60(2):247–253. [PMC free article] [PubMed] [Google Scholar]
  3. Burgert S. L., Andersen D. W., Stegink L. D., Takeuchi H., Schedl H. P. Metabolism of aspartame and its L-phenylalanine methyl ester decomposition product by the porcine gut. Metabolism. 1991 Jun;40(6):612–618. doi: 10.1016/0026-0495(91)90052-x. [DOI] [PubMed] [Google Scholar]
  4. Campbell B. J., Forrester L. J., Zahler W. L., Burks M. Beta-lactamase activity of purified and partially characterized human renal dipeptidase. J Biol Chem. 1984 Dec 10;259(23):14586–14590. [PubMed] [Google Scholar]
  5. Danielsen E. M., Norén O., Sjöström H., Ingram J., Kenny A. J. Proteins of the kidney microvillar membrane. Aspartate aminopeptidase: purification by immunoadsorbent chromatography and properties of the detergent- and proteinase-solubilized forms. Biochem J. 1980 Sep 1;189(3):591–603. doi: 10.1042/bj1890591. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Dubreuil P., Fulcrand P., Rodriguez M., Laur J., Bali J. P., Martinez J. ACE-like hydrolysis of gastrin analogs and CCK-8 by fundic mucosal cells of different species with release of the amidated C-terminal dipeptide. Biochim Biophys Acta. 1990 Jun 19;1039(2):171–176. doi: 10.1016/0167-4838(90)90182-f. [DOI] [PubMed] [Google Scholar]
  7. Gee N. S., Kenny A. J. Proteins of the kidney microvillar membrane. The 130 kDa protein in pig kidney, recognized by monoclonal antibody GK5C1, is an ectoenzyme with aminopeptidase activity. Biochem J. 1985 Sep 15;230(3):753–764. doi: 10.1042/bj2300753. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Grima M., Welsch C., Michel B., Barthelmebs M., Imbs J. L. In vitro tissue potencies of converting enzyme inhibitors. Prodrug activation by kidney esterase. Hypertension. 1991 Apr;17(4):492–496. doi: 10.1161/01.hyp.17.4.492. [DOI] [PubMed] [Google Scholar]
  9. Kessler M., Acuto O., Storelli C., Murer H., Müller M., Semenza G. A modified procedure for the rapid preparation of efficiently transporting vesicles from small intestinal brush border membranes. Their use in investigating some properties of D-glucose and choline transport systems. Biochim Biophys Acta. 1978 Jan 4;506(1):136–154. doi: 10.1016/0005-2736(78)90440-6. [DOI] [PubMed] [Google Scholar]
  10. Lipton W. E., Li Y. N., Younoszai M. K., Stegink L. D. Intestinal absorption of aspartame decomposition products in adult rats. Metabolism. 1991 Dec;40(12):1337–1345. doi: 10.1016/0026-0495(91)90040-4. [DOI] [PubMed] [Google Scholar]
  11. Littlewood G. M., Hooper N. M., Turner A. J. Ectoenzymes of the kidney microvillar membrane. Affinity purification, characterization and localization of the phospholipase C-solubilized form of renal dipeptidase. Biochem J. 1989 Jan 15;257(2):361–367. doi: 10.1042/bj2570361. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Oppermann J. A., Muldoon E., Ranney R. E. Metabolism of aspartame in monkeys. J Nutr. 1973 Oct;103(10):1454–1459. doi: 10.1093/jn/103.10.1454. [DOI] [PubMed] [Google Scholar]
  13. Stephenson S. L., Kenny A. J. Metabolism of neuropeptides. Hydrolysis of the angiotensins, bradykinin, substance P and oxytocin by pig kidney microvillar membranes. Biochem J. 1987 Jan 1;241(1):237–247. doi: 10.1042/bj2410237. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Tieku S., Hooper N. M. Inhibition of aminopeptidases N, A and W. A re-evaluation of the actions of bestatin and inhibitors of angiotensin converting enzyme. Biochem Pharmacol. 1992 Nov 3;44(9):1725–1730. doi: 10.1016/0006-2952(92)90065-Q. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Tobey N. A., Heizer W. D. Intestinal hydrolysis of aspartylphenylalanine--the metabolic product of aspartame. Gastroenterology. 1986 Oct;91(4):931–937. doi: 10.1016/0016-5085(86)90697-9. [DOI] [PubMed] [Google Scholar]

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