Abstract
1. A highly active and electrophoretically homogeneous dipeptidase was purified from the soluble extracts of monkey small-intestinal mucosa. 2. By gel-filtration studies the molecular weight of the enzyme was found to be 107000. It is composed of two identical, subunits of molecular weight 54000. 3. A paper-chromatographic method of dipeptidase assay was developed to overcome some of the difficulties encountered in the generally used spectrophotometric procedure. By using this method, the Km and k0 values of a few substrates were determined. 4. The substrate specificity of the enzyme was investigated in great detail with substrates of a wide range of possible structural types. The enzyme hydrolyses a very large proportion of the range of dipeptides tested. This enzyme, which exhibits such a wide range of action, has been termed the `master' dipeptidase of the intestine. Glycylglycine, glycyl-l-proline, glycyl-l-histidine, l-prolylglycine and some of the arginine- and aspartic acid-containing dipeptides were not substrates and are possibly hydrolysed by other peptidases. These results therefore suggest that in the intestine the number of dipeptidases is rather limited. 5. In the light of these findings, the implications on the role of dipeptidases in intestinal peptide transport are discussed.
Full text
PDF






Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adibi S. A. Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption. J Clin Invest. 1971 Nov;50(11):2266–2275. doi: 10.1172/JCI106724. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Andrews P. The gel-filtration behaviour of proteins related to their molecular weights over a wide range. Biochem J. 1965 Sep;96(3):595–606. doi: 10.1042/bj0960595. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Asatoor A. M., Cheng B., Edwards K. D., Lant A. F., Matthews D. M., Milne M. D., Navab F., Richards A. J. Intestinal absorption of two dipeptides in Hartnup disease. Gut. 1970 May;11(5):380–387. doi: 10.1136/gut.11.5.380. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Berg N. O., Dahlqvist A., Lindberg T., Nordén A. Intestinal dipeptidases and disaccharidases in celiac disease in adults. Gastroenterology. 1970 Oct;59(4):575–582. [PubMed] [Google Scholar]
- Chrambach A., Reisfeld R. A., Wyckoff M., Zaccari J. A procedure for rapid and sensitive staining of protein fractionated by polyacrylamide gel electrophoresis. Anal Biochem. 1967 Jul;20(1):150–154. doi: 10.1016/0003-2697(67)90272-2. [DOI] [PubMed] [Google Scholar]
- DAVIS B. J. DISC ELECTROPHORESIS. II. METHOD AND APPLICATION TO HUMAN SERUM PROTEINS. Ann N Y Acad Sci. 1964 Dec 28;121:404–427. doi: 10.1111/j.1749-6632.1964.tb14213.x. [DOI] [PubMed] [Google Scholar]
- Das M., Radhakrishnan A. N. Substrate specificity of a highly active dipeptidase purified from monkey small intestine. Biochem J. 1972 Jun;128(2):463–465. doi: 10.1042/bj1280463. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Heizer W. D., Laster L. Peptide hydrolase activities of the mucosa of human small intestine. J Clin Invest. 1969 Jan;48(1):210–228. doi: 10.1172/JCI105970. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hellier M. D., Perrett D., Holdsworth C. D., Thirumalai C. Absorption of dipeptides in normal and cystinuric subjects. Gut. 1971 Jun;12(6):496–497. [PubMed] [Google Scholar]
- Josefsson L., Lindberg T. Intestinal dipeptidases. I. Spectrophotometric determination and characterization of dipeptidase activity in pig intestinal mucosa. Biochim Biophys Acta. 1965 Jul 29;105(1):149–161. doi: 10.1016/s0926-6593(65)80183-7. [DOI] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Orlowski M., Meister A. The gamma-glutamyl cycle: a possible transport system for amino acids. Proc Natl Acad Sci U S A. 1970 Nov;67(3):1248–1255. doi: 10.1073/pnas.67.3.1248. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peters T. J. The subcellular localization of di- and tri-peptide hydrolase activity in guinea-pig small intestine. Biochem J. 1970 Nov;120(1):195–203. doi: 10.1042/bj1200195. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weber K., Osborn M. The reliability of molecular weight determinations by dodecyl sulfate-polyacrylamide gel electrophoresis. J Biol Chem. 1969 Aug 25;244(16):4406–4412. [PubMed] [Google Scholar]