title: On the possibilities of existence of enzymatic hydrolysis in the membranes themselves of the intestinal epithelial cells.
abstract: On the basis of literary data is made a profound survey of the place of the final stages of the sugars and peptides hydrolysis in the small intestine. It is pointed out that whereas it has been proved for the oligosaccharides to be situated on the surface of the enterocyte membranes the discussion on the cytoplasmic and membrane localization of the most dipeptidases has not ended up yet. In our own experimental investigation it has been established that the repeated washing of the small intestine with Ringer solution reduces the maltase activity whereas the glycyl-glycin dipeptidase activity does not change. This confirms the surface membrane localization of the disaccharidase while the dipeptidase is evidently not there. Due to the low pH in the cytoplasm the glycyl-glycin-dipeptidase is considered hardly likely to be localized intracellularly. A hypothesis is advanced according to which this enzyme is structurally related to the enterocyte membranes, his catalytic centre being in the membranes themselves. In this way hydrolysis is realized in the membrane pores as well, which allows the supposition that there exists intramembrane digestion.
authors.affiliation: Department of Hygiene, Ecology and Occupational Diseases, Higher Medical School, Sofia, Bulgaria.
authors.forename: B
authors.initials: B
authors.lastname: Popov
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology / Q000648:ultrastructure; D004150:Dipeptidases / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004186:Disaccharidases / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology / Q000648:ultrastructure; D006868:Hydrolysis; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D004151:Dipeptides; D004186:Disaccharidases; D000520:alpha-Glucosidases; D004150:Dipeptidases