Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Interactions of lipids and proteins in isolated rat intestinal microvillus membranes were examined by studying the temperature dependence of enzyme activities and of D-glucose transport in relation to the membrane lipid thermotropic transition observed by fluorescence polarization (26 +/- 2 degrees C) and differential scanning calorimetry (23--39 degrees C). Two groups of activities were defined. Enzymes of the first group, comprising lactase, maltase, sucrase, leucine aminopeptidase, and gamma-glutamyl transpeptidase, all yielded a single slope on the Arrhenius plot in the range 10--40 degrees C and did not appear to experience functionally the effects of the lipid thermotropic transition. Each activity of the second group, comprising calcium- and magnesium-dependent adenosine triphosphatases, p-nitrophenylphosphatase, and D-glucose transport, showed a change in the slope of the Arrhenius plot in the range 25--30 degrees C, corresponding to the lower region of the lipid transition. The terms "extrinsic" and "intrinsic" activities could be applied to these groups. Delipidation of the particulate p-nitrophenylphosphatase removed the discontinuity in the Arrhenius plot. Subsequent relipidation with a variety of lipids restored a break point, but the temperature corresponded to the original discontinuity (25--29 degrees C) rather than to the phase transition temperature of the exogenous lipid added.
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PMID:Functional interactions of lipids and proteins in rat intestinal microvillus membranes. 3 92

We adapted the Weiser method, previously used to fractionate enterocytes of rat and rabbit intestine, to the much smaller intestine of mice. By histological, morphometric, enzymatic, histochemical, and immunocytochemical evidence, the method succeeded in removing mouse enterocytes sequentially along the crypt-villus axis while preserving cell viability and minimizing mixing among cell fractions. Activities of three brush-border enzymes [alkaline phosphatase (AP), sucrase, and gamma-glutamyl transpeptidase (GGP)] varied simultaneously with dietary substrate level, intestinal region, and position along the crypt-villus axis. All three enzymes proved to be stimulated by dietary substrate: sucrase by dietary sucrose, AP and GGP by dietary protein. We also studied cell migration rates and life-times by autoradiography and by our modified Weiser method. By both methods, injected [3H]thymidine after short times was virtually confined to crypt cells, whereas after 40-48 h it was distributed from the crypt over the whole villus except for the villus tip. Villus height decreased twofold from duodenum to ileum, parallel to the regional decrease in cell migration rates because the cell lifetime of 68 h was independent of region. When we varied dietary carbohydrate and protein levels reciprocally while maintaining protein above the maintenance level, both cell migration rate and cell lifetime proved independent of diet.
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PMID:Regulation of brush-border enzyme activities and enterocyte migration rates in mouse small intestine. 135 87

The effects of variation in dietary protein content have been investigated on brush border glycosylation and enzyme activities in mice small intestine. The comparison of different parameters was made between the mice fed 30% (high protein, HP) and 18% protein (pair-fed, PF, and ad libitum-fed) for 21 days. The activities of brush border sucrase, lactase, p-nitrophenyl (PNP)-beta-D-glucosidase and PNP-beta-D-galactosidase were reduced in the HP diet-fed mice compared to PF and ad libitum-fed controls. Alkaline phosphatase and leucine amino-peptidase activities were significantly enhanced while gamma-glutamyl transpeptidase activity was unaltered under these conditions. Total hexoses and sialic acid content in the brush borders were reduced significantly in the test group compared to the controls while hexosamine and fucose contents remained essentially similar in different groups. The results on the binding of wheat germ agglutinin and Ulex europaeus agglutininI to microvillus membranes corroborated the chemical analysis data on sialic acid and fucose contents of the membranes. Peanut agglutinin binding was enhanced in mice from the HP group. Incorporation of (14C)-mannose into membranes was significantly less in HP diet-fed mice. These results indicate that the feeding of HP diet to mice brings about marked alterations in small intestinal epithelial cell surface glycosylation and enzyme functions.
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PMID:Intestinal epithelial cell surface glycosylation in mice. I. Effect of high-protein diet. 149 56

The common hookworm (Ancylostoma ceylanicum) infection of humans was studied in golden hamsters model system. Significant biochemical modulations were observed in hamster jejunal brush border membrane (BBM), the primary site of infection. Analysis of BBM at the peak of infection (3-weeks) revealed a marked decrease in the activities of sucrase, lactase and maltase, while activities of alkaline phosphatase, (Ca2+ + Mg2+)-ATPase and gamma-glutamyl transpeptidase were increased. Kinetic studies conducted with maltase, a superficially localised enzyme of jejunal BBM, revealed loss of enzyme active site during the infection. Among other constituents, the levels of cholesterol and triglycerides were significantly decreased with slight increase in phospholipid content in the infected animals. The hookworm infection also caused a decline in total hexose content indicating an altered membrane glycocalyx. Conversely, there was significant enhancement of hydroxyproline and sialic acid contents. SDS-PAGE analysis showed an enhancement in both low and high molecular weight proteins in jejunal BBM preparations of the infected group. Gel electrophoresis of glycoproteins further revealed the appearance of two additional peaks in the low molecular weight region and concomitant disappearance of a peak in the high molecular weight region. These results strongly support the view that the hookworm infection causes severe damage not to the site of attachment alone but also to the entire cell lining of the jejunum and therefore could influence overall digestion and absorption.
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PMID:Biochemical analysis of jejunal brush border membrane of golden hamster: pathogenic modulations due to ancylostomiasis. 159 19

The effect on rats of oral doses (38.66 mM/kg body wt) of propane-1,2-diol (PD) administered daily for 10 (Group 1), 20 (Group 2), and 30 days (Group 3) was investigated. Weight gain was initially retarded (P less than 0.05) in Group 1, but was later reversed and elevated significantly (P less than 0.05) in Groups 2 and 3 as compared with their respective controls receiving an equal volume of saline. PD showed a tendency toward enhancing the activities of various enzymes involved in terminal digestion, with the significant effect exerted in few groups on sucrase (P less than 0.05), lactase (P less than 0.05), and gamma-glutamyl transpeptidase (P less than 0.05) when compared with the respective controls. Absorption of D-glucose, glycine, L-aspartic acid, L-lysine, and calcium was elevated and was especially significant in Groups 2 and 3 (P less than 0.001). The structural integrity of the jejunal surface was retained for the most part. A similar examination of the effects of PD was also carried out in vitro to ascertain whether PD itself or its metabolites are involved in its action. The in vitro effects of propane-1,2-diol were compared with those of the more toxic compound propane-1,3-diol. The former exerted greater inhibitory action on the activities of the disaccharidases. The degree of inhibition was in the order sucrase much greater than lactase greater than maltase. The kinetic data revealed that inhibition by 1,2-diol in native and detergent solubilized sucrase is noncompetitive, with Ki values in the range of 0.35-0.41 M. The two diols did not alter the nutrient transport in the brush border membrane vesicles. The present work on rats indicates that PD may influence the intestinal digestive and absorptive functions in vivo and that this in vivo effect of PD is different from that observed in vitro suggesting that the nutritional and toxicological effect of PD may be mediated by different mechanisms.
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PMID:The effect of propane-diols on the intestinal uptake of nutrients and brush border membrane enzymes in the rat. 188 24

The effect of methylglyoxal on protein -SH and -NH2 groups in cytosolic and membranous fractions of epithelial cells lining the gastrointestinal tract of rat was investigated, using isolated villus and crypt cells (enterocytes) and colonocytes. It was found that 11-12% cytosolic protein -SH and 14-17% membrane protein -SH groups were lost when villus and crypt cells were treated with 2 mM methylglyoxal. In colonocytes, the corresponding loss in protein -SH groups was 46 and 30% under the same treatment. Similarly, 27-37% protein -NH2 group in the cytosolic fraction and 18-19% protein -NH2 group in membranous fractions of the enterocytes were lost by 2 mM methylglyoxal treatment. In colonocytes, the loss of protein -NH2 group was 30 and 15% in cytosolic and membranous fractions, respectively, under the same treatment. Effect of methylglyoxal on activity of various brush border enzymes such as alkaline phosphatase, gamma-glutamyl transpeptidase, leucine aminopeptidase, Mg2(+)-ATPase, sucrase and lactase was also studied. Alkaline phosphatase and gamma-glutamyl transpeptidase activities were inhibited to the extent of 30 and 15% respectively. There was no significant change in the activities of other enzymes after treating the brush border vesicles with 2 mM methylglyoxal. These findings show that methylglyoxal can cause loss of protein thiol and amino groups and enzyme activity in mucosal cells of rat gastrointestinal tract and the effect is more pronounced in colonocytes, which are in constant contact with bacterial metabolites.
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PMID:Effect of methylglyoxal on protein thiol and amino groups in isolated rat enterocytes and colonocytes and activity of various brush border enzymes. 234 Nov 60

The activities of intestinal brush border membrane (BBM) enzymes alkaline phosphatase, maltase, lactase, sucrase, gamma-glutamyl transpeptidase and leucine aminopeptidase were determined in intestinal homogenates and purified BBMs from control, heat-stable and heat-labile enterotoxin treated mice. The activities of all the enzymes except lactase were decreased significantly (p less than 0.01) in homogenates while increased significantly (p less than 0.001) in BBMs of experimental groups as compared to controls. Calmodulin activities were increased significantly (p less than 0.01) as compared to control in heat-stable enterotoxin treated mice but remained unaltered in heat-labile enterotoxin treated mice. DNA contents of intestinal homogenates were decreased in experimental groups demonstrating the decrease in cell number in these groups. The altered BBM enzyme activities could not be attributed to changes in calmodulin activities. The increase in enzyme activities in BBMs may reflect a compensatory phenomenon in the remaining cells.
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PMID:Effect of heat-stable and heat-labile enterotoxins of Escherichia coli on intestinal brush border membrane enzymes of mice. 257 May 78

Brush-border membranes prepared from proximal and distal human small intestine were characterized with respect to lipid fluidity, lipid composition, and protein-lipid interactions. Steady-state fluorescence polarization and differential polarized phase fluorometry revealed that the "static" and "dynamic" rotational components of fluidity (assessed by r infinity values of 1,6-diphenyl-1,3,5-hexatriene and r values of 12-anthroylstearate, respectively) were greater in the distal membranes compared with their proximal counterparts. The lipid fluidity of distal brush-border membranes was also greater as measured by excimer/monomer fluorescence ratio intensities of pyrene decanoate. A lower molar ratio of cholesterol/phospholipid in the distal membranes was responsible for these regional fluidity differences. Lipid thermotropic transitions were detected at 26-28 degrees C using 1,6-diphenyl-1,3,5-hexatriene in proximal and distal membranes. Arrhenius plots of p-nitrophenylphosphatase and gamma-glutamyl transpeptidase activities demonstrated breakpoints in the vicinity of the lipid thermotropic transition temperatures (28-30 degrees C), whereas maltase and sucrase yielded a single activity slope over the range of 10-40 degrees C. Moreover, 50 mM benzyl alcohol fluidized proximal brush-border membranes and increased p-nitrophenylphosphatase activity in this membrane. This agent also shifted the phase transition temperature of the membrane and breakpoint temperature of this enzymatic activity from approximately 28 degrees C to 19 degrees C. These findings demonstrate that differences in human small intestinal brush-border membrane lipid fluidity and lipid composition exist between proximal and distal regions of this organ. Furthermore, alterations in fluidity and/or lipid composition modulate p-nitrophenylphosphatase and gamma-glutamyl transpeptidase but not sucrase or maltase activities in these membranes.
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PMID:Protein-lipid interactions in human small intestinal brush-border membranes. 259 11

The effect of different concentrations of sodium fluoride (12, 24, 48 and 96 mM), instilled into the ligated intestine of anaesthetized rats for 30 min, on intestinal permeability and some brush border enzymes was investigated. A concentration-dependent change in permeability was observed; there was an increase in the volume of luminal fluid and altered net transport of Na+ and K K+ ions. The change in permeability was accompanied by increased protein, sialic acid and nucleic acid accumulation in the luminal fluid. A striking loss of brush border alkaline phosphatase (41%) sucrase (59%) and gamma-glutamyl transpeptidase (73%) activities was observed at 96 mM fluoride with a corresponding increase in the activity of these enzymes in luminal fluid, while 12 mM fluoride did not produce any significant effect. This loss was probably not due to an inhibition of the enzymes by fluoride since in vitro experiments did not produce any such effect over a range of NaF concentrations (0-32 mM) except on alkaline phosphatase activity at the 32 mM NaF concentration. The studies, therefore, suggest that the loss of brush-border enzyme activities observed in situ was most probably due to membrane damage caused by the high fluoride concentration.
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PMID:Effects of fluoride on membrane permeability and brush border enzymes of rat intestine in situ. 286 74

The protein induced modifications of the small bowel mucosa from ovalbumin-sensitised mouse have been studied in organ culture. A decrease in gamma-glutamyl transpeptidase, alkaline phosphatase, lactase, sucrase, and glucoamylase activities was observed in the explants cultured in the presence of ovalbumin. In contrast, a large increase of those enzymatic activities was noted in the culture media, the overall effect observed being a net stimulation of the total enzymatic activities of the culture system. The enzymes accumulated in the particulate fraction of the medium (brush border membrane fraction) suggesting an increased turnover of membrane components by a process of shedding or microvesiculation. This model serves as a useful tool in evaluating the local response of the small bowel mucosa induced by a specific protein.
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PMID:Establishment of an animal model of ovalbumin sensitised mouse to study protein induced enteropathy. 379 13


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