Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of monensin and colchicine on the biogenesis of aminopeptidase N (EC 3.4.11.2), aminopeptidase A (EC 3.4.11.7), dipeptidyl peptidase IV (EC 3.4.14.5), sucrase (EC 3.2.1.48)-isomaltase (EC 3.2.1.10) and maltase-glucoamylase (EC 3.2.1.20) was studied in organ-cultured pig small-intestinal explants. On the ultrastructural level, monensin (1 microM) caused an increasingly extensive dilation and vacuolization of the Golgi complex during 4h exposure of the explants. On the molecular level, the effect of monensin was twofold. (1) The processing from the initial high-mannose-glycosylated form to the mature complex-glycosylated form was arrested. For some of the enzymes studied, intermediate stages between the high-mannose and complex forms could be seen, probably corresponding to 'trimmed' or partially complex-glycosylated polypeptides. (2) Labelled microvillar enzymes failed to reach their final destination. These findings suggest the involvement of the Golgi complex in the post-translational processing and transport of microvillar enzymes. The presence in the growth medium of colchicine (50 micrograms/ml) caused a significant inhibition of the appearance of newly synthesized enzymes in the microvillar membrane during a 3 h labelling period. Since synthesis and post-translational modification of the microvillar enzymes were largely unaffected by colchicine, the results obtained suggest that microtubules play a role in the final transport of the enzymes from the Golgi complex to the microvillar membrane.
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PMID:Biosynthesis of intestinal microvillar proteins. Role of the Golgi complex and microtubules. 665 78

The activities of microvillus aminopeptidase (microsomal, EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.-), glycyl-leucine dipeptidase (EC 3.4.13.11), proline dipeptidase (EC 3.4.13.9), sucrase (EC 3.2.1.48) and gamma-glutamyl transpeptidase (EC 2.3.2.2) were measured in peroral intestinal biopsies taken from patients with coeliac disease in the acute phase and in remission. A comparison with the amounts of corresponding activities from a reference group showed that all the measured activities were significantly decreased in the acute phase of the disease. In patients in remission only microvillus aminopeptidase and dipeptidyl dipeptidase IV displayed a substantial depression as compared to the reference group. It is suggested that a primary mucosal digestion defect will result in lack of substrate for other intestinal enzymes. This is a situation comparable to starvation and may explain the variation in the grade of restitution for the different enzymes.
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PMID:Intestinal peptidases and sucrase in coeliac disease. 700 82

Explants of pig small intestine were maintained at 37 degrees C in organ culture for periods up to 24 h in a system using Trowell T-8 medium supplemented with 10% foetal-calf serum. The mucosal morphology was well preserved during culture, as judged by light and electron microscopy. The explant contents of protein and two brush-border enzymes, microvillus aminopeptidase (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5), were not significantly modified during culture compared with controls, but a moderate, continuous release of both protein and enzyme activities into the medium was observed. Continuous labelling with [35S]methionine resulted in an even incorporation of radioactivity in the protein components, and the rate of labelling only moderately decreased over the 24 h period. The polypeptide compositions of sucrase (EC 3.2.1.48)--isomaltase (EC 3.2.1.10), maltase--glucoamylase (EC 3.2.1.20) lactase (EC 3.2.1.23)--phlorizin hydrolase (EC 3.2.1.62), microvillus aminopeptidase and aspartate aminopeptidase (EC 3.4.11.7) synthesized during culture were studied, and some were found to be similar to those of the pro-forms of the enzymes isolated from animals that had had their pancreatic duct disconnected 3 days before being killed. These results confirmed earlier findings of the existence of pro-forms of some of the microvillar enzymes and thus indicate a low activity of pancreatic proteinases in the culture system.
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PMID:Biosynthesis of intestinal microvillar proteins. Characterization of intestinal explants in organ culture and evidence for the existence of pro-forms of the microvillar enzymes. 709 36

The amounts of lactase (EC 3.2.1.23), sucrase (EC 3.2.1.48), maltase (EC 3.2.1.20), microvillus aminopeptidase (microsomal EC3.4.11.2), and dipeptidyl peptidase IV (EC 3.4.14.X) in biopsies from proximal jejunum and distal ileum were studied by quantitative crossed immunoelectrophoresis and enzymatic assays in obese patients one and six months after jejunoileal bypass operation and compared with peroperative levels. They were related to DNA and protein content. The protein/DNA ratio fell 28-43% postoperatively. Except for ileal lactase and sucrase all enzymes showed decreased levels when expressed per mg protein and an even more pronounced decrease when related to DNA. Lactase and sucrase levels in ileum were increased or unchanged. A constant correlation between the amount of immunoreactive enzyme protein and enzymatic activity was shown for all enzymes except maltase. The results suggest that the bypass operation is followed by an increased amount of enterocytes devoid of or low in enzymatic activity and protein content. The amounts of lactase and sucrase in ileum are increased in relation to the other enzymes. No immunoreactive enzymes with zero or depressed activity were detected.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins: cellular alterations in the levels of brush border enzymes after jejunoileal bypass operation. 742 30

A method for analysing microgram amounts of microvillar membranes by two-dimensional electrophoresis (protein mapping) is described, and has been used to characterize the microvillar proteins of the small intestine of German shepherd, corgi, and beagle dogs. Detergent-solubilized microvillar membranes were radiolabelled with 14C and separated by isoelectric focussing followed by SDS-PAGE. Proteins were detected fluorographically and glycoproteins by lectin-affinity staining. The microvillar hydrolases alkaline phosphatase and dipeptidyl aminopeptidase IV were identified by active-site labelling and aminopeptidase N by immunoprecipitation. Changes following pancreatic duct diversion were consistent with accumulation of pro-sucrase-isomaltase and diminished expression of the sucrase and isomaltase subunits. Cytoskeletal proteins were concentrated in the core fraction remaining after extraction of microvillar membranes with Triton X-100. There were no consistent differences between dogs of different breed, and the canine protein maps were similar to the human.
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PMID:Characterization of microvillar membrane proteins of dog small intestine by two-dimensional electrophoresis. 758 24

The present study was designed to investigate the effects of grape seed tannins on rat intestinal alkaline phosphatase (AP), sucrase and dipeptidyl peptidase IV (DPP IV) activities. An experiment was performed in vivo by dietary supplementation with 2% tannins; this diet was tested on an experimental group of rats; a control group received a diet without tannins. After 31 days, tannins intake significantly decreased middle-jejunal AP from 123 to 45 mU/mg protein and sucrase activities from 310 to 195 mU/mg protein, while no significant difference appeared at the duodenal stage (p < 0.05). Ileal DPP IV activity was also significantly reduced (p < 0.05) from 190 to 110 mU/mg protein after tannin intake. Using in vitro experiments on purified brush border membranes, AP activity was found to be inhibited by grape tannins; this inhibition was prevented by the detergent Triton X-100. The addition of pancreatic-biliary (PB) juice to the incubation medium prevented or reversed the tannin-inhibited enzyme activity. The present data indicate that in the duodenal lumen, alkalinity and detergency from the PB secretion neutralized the ability of tannins to inactivate brush border hydrolase activities and suggest that enzyme inhibition took place once bile salts were reabsorbed while moving down the gut. This was confirmed by in vitro experiments where sucrase and DPP IV activities inhibited by grape seed tannins were largely recovered after the addition of PB juice to the incubation medium.
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PMID:Effect of grape seed tannins on the activity of some rat intestinal enzyme activities. 778 71

Epidemiological and in vivo and in vitro experimental studies have suggested that fermented milks may interfere with the emergence and/or the development of colon cancer. The results, however, remain inconclusive. This prompted us to develop a new approach based on the use of HT-29, a cultured human colon cancer cell line, to study at the cellular level the effect of fermented milks on colon cancer cell growth and differentiation characteristics. Undifferentiated HT-29 cells have been grown in the continuous presence of milks fermented by one of the following bacterial populations: Lactobacillus helveticus, Bifidobacterium, L.acidophilus or a mix of Streptococcus thermophilus and L. bulgaricus. Penicillin G was added to the cell culture medium, resulting in a complete blockade of bacterial growth without significant effect on bacterial viability. One out of the four bacteria species studied, namely L.acidophilus, was without effect on both cell growth and differentiation. The three other bacterial strains induced a significant, although variable, reduction in the growth rate of HT-29 cells, which resulted in a 10-50% decrease in the cell number at steady-state (i.e. at cell confluency). The most efficient strains in lowering the HT-29 growth rate were L. helveticus and Bifidobacterium. Concomitantly, the specific activities of dipeptidyl peptidase IV (DPP IV), a sensitive and specific marker of HT-29 cell differentiation, and that of three other brush border enzymes (sucrase, aminopeptidase N and alkaline phosphatase) were significantly increased, thus suggesting that these cells may have entered a differentiation process. Altogether, these results indicate that the use of cultured colon cancer cells may be a useful tool to further study the effect of fermented milks on colon cancer and that bacterial strains may exert a different and specific effect on cancer cell growth and differentiation when used in fermented milk products.
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PMID:Use of HT-29, a cultured human colon cancer cell line, to study the effect of fermented milks on colon cancer cell growth and differentiation. 785 55

This study describes the properties of a clone of immortalized cells (m-ICc12 cells) derived from the bases of small intestinal villi from 20-day-old fetuses of L-type pyruvate kinase (L-PK)/ TAg1 transgenic mice. The mice harbor the simian virus 40 large T antigen under the control of the 5' regulatory sequence from the L-PK gene. m-ICc12 cells expressed nuclear large T antigen, had a prolonged life span, and were nontumorigenic when injected into nude mice. They formed confluent monolayers of cuboid cells separated by tight junctions, developed dense, short apical microvilli, and formed domes. They also possessed cytokeratins, villin, aminopeptidase N, dipeptidyl-peptidase IV, and glucoamylase and retained crypt cell features, including intracellular sucrase isomaltase and alpha-L-fucose glycoconjugates accumulation and expression of the polymeric immunoglobulin receptor and the cystic fibrosis transmembrane conductance regulator gene. Thus the m-ICc12 cell line obtained by targeted oncogenesis in transgenic mice maintained in culture several important properties and differentiated functions of intestinal crypt cells.
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PMID:Transimmortalized mouse intestinal cells (m-ICc12) that maintain a crypt phenotype. 876 49

Glucagon-like peptide-2 (GLP-2) stimulates small intestinal growth through induction of intestinal epithelial proliferation. To examine the physiology of GLP-2-induced bowel, mice were treated with GLP-2 (2.5 micrograms) or vehicle for 10 days. Small intestinal weight increased to 136 +/- 2% of controls in GLP-2-treated mice, in parallel with 1.4 +/- 0.1- and 1.9 +/- 0.5-fold increments in duodenal RNA and protein content, respectively (P < 0.05-0.001). Similarly, the activities of duodenal maltase, sucrase, lactase, glutamyl transpeptidase, and dipeptidyl-peptidase IV (215 +/- 28% of controls; P < 0.001) were increased by GLP-2. Oral or duodenal administration of glucose or maltose did not reveal any differences in the ability of GLP-2-treated mice to absorb these nutrients, possibly because of decreases in expression of the glucose transporters sodium-dependent glucose transporter-1 (SGLT-1) and GLUT-2. In contrast, absorption of leucine plus triolein was increased after duodenal administration in GLP-2-treated mice (P < 0.01-0.001). Finally, GLP-2 did not alter other markers of intestinal or pancreatic gene expression, including levels of mRNA transcripts for ornithine decarboxylase, multidrug resistance gene, amylase, proglucagon, proinsulin, and prosomatostatin. Thus induction of intestinal growth by GLP-2 in wild-type mice results in a normal-to-increased capacity for nutrient digestion and absorption in vivo.
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PMID:Intestinal function in mice with small bowel growth induced by glucagon-like peptide-2. 922 51

Coeliac disease is a human, genetically linked, disorder which develops in gluten-sensitive persons. The aim of this study was to investigate the effect of prolonged feeding of gliadin, a major fraction of gluten, on enzyme activities of enterocyte brush border membrane enzymes in rats, mice and pigs. Brush-border membranes were isolated from mucosal scrapings of the small intestine of 21-d-old rat pups hand-fed with formula milk diet, two-month-old nu/nu and +/+ BALB/c mice and two-month-old piglets fed three times a week starting at birth with high doses of gliadin. Activities of lactase, sucrase and dipeptidyl peptidase IV (DPP IV) were determined. Individual animal models differed in their response to gliadin feeding. In comparison with albumin fed controls the activities of DPP IV and lactase were decreased in rat pups, nu/nu BALB/c mice and piglets. DPP IV activity was mostly affected in the ileum of rats and piglets fed with gliadin starting at birth. On the other hand, lactase and sucrase activities of nu/nu BALB/c mice and piglets decreased to the largest extent in jejunum.
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PMID:Brush border enzyme activities in the small intestine after long-term gliadin feeding in animal models of human coeliac disease. 982 9


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