title: Intestinal brush border peptidases: activities in normal and abnormal peroral intestinal biopsy specimens.
abstract: Discriminating substrates were used to develop assays that accurately measure the activity of each of four brush border peptidases in peroral jejunal biopsy specimens. Seventy-five biopsy specimens, 43 normal and 32 abnormal, were assayed for aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2), and disaccharidases, and 37 of these were assayed for membrane glycylleucine peptidase and Zn2+-stable aspartyllysine peptidase. Peptidase levels in normal biopsy specimens from males and females did not differ. Only aminopeptidase A levels changed significantly with age. The mean +/- SD units per gram of protein for each enzyme in peroral biopsy specimens of normal intestine were aminopeptidase A 1.7 +/- 0.7 for children and 3.1 +/- 1.3 for adults, membrane glycylleucine peptidase 16.3 +/- 10.6, aminopeptidase N 35.5 +/- 13.2, and Zn2+-stable aspartyllysine peptidase 42.6 +/- 28.5. In abnormal biopsy specimens, levels of three of the peptidases and the disaccharidases were significantly decreased, 37% to 51%. In contrast, aminopeptidase N activity was decreased only 7% in the abnormal biopsy specimens. These results provide a basis for further studies investigating the role of brush border peptidases in normal digestion and various pathologic states, including the search for individuals with brush border peptidase deficiencies.
authors.forename: N A
authors.initials: NA
authors.lastname: Tobey
authors.forename: L E
authors.initials: LE
authors.lastname: Lyn-Cook
authors.forename: M H
authors.initials: MH
authors.lastname: Ulshen
authors.forename: W D
authors.initials: WD
authors.lastname: Heizer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D000626:Aminopeptidases / Q000378:metabolism; D001706:Biopsy; D018826:CD13 Antigens; D002648:Child; D002675:Child, Preschool; D004150:Dipeptidases / Q000378:metabolism; D005260:Female; D005615:Freezing; D043384:Glutamyl Aminopeptidase; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000473:pathology; D008297:Male; D008871:Microvilli / Q000201:enzymology / Q000473:pathology; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000378:metabolism*; D012737:Sex Factors
chemical_list: D010447:Peptide Hydrolases; D000626:Aminopeptidases; D018826:CD13 Antigens; D043384:Glutamyl Aminopeptidase; D004150:Dipeptidases; C047765:aspartyllysine peptidase; C020825:cytosol non-specific dipeptidase