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)

Seven subjects were fed a 3,000 kcal defined formula diet daily for 19 days. Except for one 5-day period, 50% of the total caloric intake was provided as either oral or intravenous glucose. The study was divided into four periods as follows: period I lasted 5 days and provided 50% of calories as glucose; period II lasted 5 days and provided no carbohydrate (70% fat and 30% protein); period III lasted 4 days and provided 50% of calories as intravenous glucose and 50% of calories as oral fat plus protein; period IV lasted 5 days and provided 50% of calories as oral glucose. Intestinal biopsy specimens were taken on days 3 and 5 of each period, except period III when biopsies were done only on day 4. No change in intestinal morphology occurred during the study. The carbohydrate-free diet caused the alpha-glucosidase (maltase and sucrase) activities to decrease significantly from that seen with the glucose diet. Sucrase decreased from 14.4 +/- 1.0 to 7.1 +/- 0.9 mumoles/min per g tissue and maltase decreased from 56.1 +/- 3.4 to 30.0 +/- 2.1 mumoles/min per g tissue. Glycolytic enzyme activities decreased during the carbohydrate-free period (pyruvate kinase decreased from 236 +/- 12 to 78 +/- 8, fructose 1-phosphate aldolase decreased from 147 +/- 6 to 53 +/- 4, fructose-1,6-diphosphate aldolase decreased from 151 +/- 8 to 55 +/- 3, and hexokinase decreased from 21 +/- 3 to 7 +/- 1 nmoles/min per mg protein, respectively). Intravenous glucose caused no change in disaccharidase activities. The enzyme activities during periods I and IV were identical and significantly higher than during period II with the exception of fructose-1,6-diphosphatase which increased during period II as compared with periods I and IV. These findings provide an explanation for the transient period of decreased tolerance to dietary sugars when patients are weaned from total parenteral feedings to enteral feedings.
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PMID:Comparison of the adaptive changes in disaccharidase, glycolytic enzyme and fructosediphosphatase activities after intravenous and oral glucose in normal men. 17 Aug 20

Various enzyme activities involved in the active transport system, glycolysis, and digestion were assayed in various parts of the gastrointestinal tracts of germfree, conventional, and gnotobiotic rats associated with indigenous bacteria. The activity levels of alkaline phosphatase, glucose 6-phosphatase, adenosine triphosphatase, and disaccharidases in the upper small intestine were highest in all parts of the gastrointestinal tracts of various kinds of gnotobiotic, conventional, and germfree rats. Alkaline phosphatase, glucose 6-phosphatase, and adenosine triphosphatase activities in the upper small intestine of germfree rats were, respectively, 2.3-, 2.9-, and 1.7-fold higher than those in conventional rats. Similar to the results of these enzymes, sucrase, maltase, trehalase, and lactase activities in the upper small intestine of germfree rats were, respectively, 1.6-, 1.5-, 2.3-, and 1.8-fold higher than those in conventional rats. In various gnotobiotic rats, enzyme activity levels were intermediate between those in germfree and conventional rats. These findings suggest that those enzymatic activities are strongly depressed by the association with the indigenous microorganisms in the epithelial mucosa of the upper small intestine of rats. The levels of pyruvate kinase, hexokinase, and lactate dehydrogenase activities were highest, respectively, in the stomach, cecum, and the upper small intestine and cecum in all parts of the gastrointestinal tracts in various kinds of gnotobiotic, conventional, and germfree rats. It was also shown that six kinds of gastrointestinal bacteria, including lactobacilli, significantly depressed the enzyme activity levels to levels between those of the germfree and conventional rats in the upper small intestine of gnotobiotic rats.
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PMID:Intestinal enzyme activities in germfree, conventional, and gnotobiotic rats associated with indigenous microorganisms. 20 6

Phytomonas sp. isolated from Euphorbia characias was adapted to SDM-79 medium. Cells isolated in the early stationary phase of growth were analyzed for their capacity to utilize plant carbohydrates for their energy requirements. The cellulose-degrading enzymes amylase, amylomaltase, invertase, carboxymethylcellulase, and the pectin-degrading enzymes polygalacturonase and oligo-D-galactosiduronate lyase were present in Phytomonas sp. and were all, except for amylomaltase, excreted into the external medium. Glucose, fructose and mannose served as the major energy substrates. Catabolism of carbohydrates occurred mainly via aerobic glycolysis according to the Embden-Meyerhof pathway, of which all the enzymes were detected. Likewise, the end-products of glycolysis, acetate and pyruvate, glycerol, succinate and ethanol were detected in the culture medium, as were the enzymes responsible for their production. Mitochondria were incapable of oxidizing succinate, 2-oxoglutarate, pyruvate, malate and proline, but had a high capacity to oxidize glycerol 3-phosphate. This oxidation was completely inhibited by salicylhydroxamic acid. No cytochromes could be detected either in intact mitochondria or in sub-mitochondrial particles. Mitochondrial respiration was not inhibited by antimycin, azide or cyanide. The glycolytic enzymes, from hexokinase to phosphoglycerate kinase, and the enzymes glycerol kinase, glycerol-3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, malate dehydrogenase and adenylate kinase, were all associated with glycosomes that had a buoyant density of about 1.24 g cm-1 in sucrose. Cytochemical staining revealed the presence of catalase in these organelles. The cytosolic enzyme pyruvate kinase was activated by fructose 2,6-bisphosphate, typical of all other pyruvate kinases from Kinetoplastida. The energy metabolism of the plant parasite Phytomonas sp. isolated from E. characias resembled that of the bloodstream form of the mammalian parasite Trypanosoma brucei.
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PMID:Characterization of carbohydrate metabolism and demonstration of glycosomes in a Phytomonas sp. isolated from Euphorbia characias. 143 59

The catabolic, NAD-specific glutamate dehydrogenase (NAD-GDH) of Neurospora crassa is under carbon catabolite repression. Cells grown on a glycolytic carbon source, such as sucrose, have low basal levels of enzyme activity. Treatment of repressed cells with either polymyxin B or amphotericin B resulted in derepression of NAD-GDH. Derepression at the transcriptional level occurred very rapidly (within 30 min) in response to polymyxin B addition but reached a plateau within 2 h. Amphotericin B-induced derepression initiated more slowly but continued for at least 6 h, resulting in a specific activity comparable to that seen with cells transferred to glutamate as the sole carbon source. These antibiotics had no significant effect upon the activities of two constitutive enzymes, pyruvate kinase and malate dehydrogenase. Curiously, only polymyxin B treatment derepressed invertase, another catabolite-repressed enzyme. The addition of 100 mM KCl to the growth medium blocked derepression by both antibiotics, but the addition of 50 mM MgCl2 only annulled derepression by polymyxin B. The ergosterol-deficient erg-1 mutant, which is resistant to amphotericin B, did not derepress NAD-GDH when treated with this drug. These results are consistent with derepression resulting from interactions of these antibiotics with the plasma membrane.
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PMID:Antibiotic-induced derepression of the NAD-specific glutamate dehydrogenase of Neurospora crassa. 282 59

The effect of resuming food intake after a period of starvation (refeeding) on the specific activities of selected rat intestinal enzymes was determined. The rate of weight gain was higher in refed animals than in control animals, without a difference in food intake. Fasting caused intestinal atrophy which reversed rapidly on refeeding. Fasting decreased the specific activities of sucrase, maltase, and galactokinase, but did not affect the specific activities of hexokinase, pyruvate kinase, or crypt thymidine kinase. Sucrase, maltase, hexokinase, pyruvate kinase, and thymidine kinase specific activities all rose above control values during refeeding. The overshoot in intestinal enzyme specific activities may help promote the rapid weight gain observed in refed rats and is an integral part of the total adaptation to fasting and refeeding.
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PMID:Refeeding after a fast in rats: effects on small intestinal enzymes. 705 2

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

In the intestine, the follicle-associated epithelium (FAE) of Peyer's patches (PP) performs Ag sampling as the first step in developing immune responses. Depending on the species, this epithelium contains 10-50% of M cells, which act as regulated gates in epithelial barriers that can be used opportunistically by pathogens to invade their host. However, the mechanisms involved in the differentiation and uptake processes of M cells are not known, in part because their limited number in the intestinal mucosa has hampered molecular and biochemical studies. In this work we provide evidence that PP lymphocytes can themselves modulate gene expression in PP in vivo and in an in vitro model of FAE. Transgenic mice carrying a reporter gene under the control of a modified L-pyruvate kinase promoter (SVPK) exhibit strong transgene expression in PP and FAE, but not in the adjacent villous cells. We used the mouse intestinal epithelial cell line m-IC(cl2) transfected with the SVPK promoter fused to beta-galactosidase to investigate the direct effect of PP lymphocytes on SVPK promoter activity. beta-Galactosidase expression was 4.4-fold higher in transfected m-IC(cl2) cells when they were cultured with PP lymphocytes. Conversely, green fluorescent protein expression was 1.8-fold lower in stably transfected differentiated intestinal Caco-2(cl1) cells with the sucrase isomaltase promoter fused to green fluorescent protein cDNA when they were cultured with PP lymphocytes, indicating that the in vivo FAE down-regulation of sucrase isomaltase promoter is transcriptionally regulated.
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PMID:Lymphoepithelial interactions trigger specific regulation of gene expression in the M cell-containing follicle-associated epithelium of Peyer's patches. 1193 21

In the apple variety 'Usterapfel', there are two known genotypes, which differ in malic acid content. One hundred days after full bloom, low-acid fruit (LA-fruit) contained 125 micromolg(-1) dry matter (DW) of malate, while the high-acid genotype (HA-fruit) reached levels up to 627 micromolg(-1) DW. There was no difference in the catalytic activity of enzymes involved in malate metabolism, such as PEPcarboxylase, malate dehydrogenase, and NADP malic enzyme. After [14C]glucose incorporation into the excised tissue of either genotype, the organic acid fraction was labeled to approximately the same extent. Furthermore, uptake of [14C]malate was significantly lower in excised tissue of LA-fruit. These findings suggest that low malate content in LA-fruit is the result of a restricted ability to accumulate malate in apple parenchyma cells. The different ability to accumulate malate had a pronounced effect on overall carbon partitioning. However, the rate of respiration and the rate of malate synthesis was similar in both genotypes. In HA-fruit, the glycolytic flux through pyruvate kinase was increased to compensate for the carbon that accumulated in the vacuole as malate. Since malate storage in the LA-fruit was restricted, it was more easily available for gluconeogenesis, and was correlated with a three-times higher activity of PEPcarboxykinase. LA-fruit showed higher concentrations of ATP, which stimulated Glc6P and fructose-6-phosphate formation. The elevated hexosephosphate content led to an enhanced partitioning of carbon into starch (+40%), hemicellulose (+104%), and sucrose (+40%) in more mature fruit. The activation of carbohydrate synthesis resulted in a significant drop in glucose-1-phosphate (Glc1P). To meet the increased demand for Glc1P, the activities of neutral and acid invertase, hexokinase, and phosphoglucomutase were higher in LA-fruit. Glucose was a more versatile substrate for this metabolic route than was fructose. It was also evident that glycolytic flux in apple was dependent on glucose level, and that the reaction catalysed by phosphoglucomutase contributed to the regulation of carbon partitioning between malate and carbohydrate polymers.
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PMID:Carbohydrate metabolism in two apple genotypes that differ in malate accumulation. 1549 4

Fluorescent-labeled invertase, a hyperglycosylated mannoprotein from Saccharomyces cerevisiae, was found to bind to Lactococcus lactis IL1403 at acidic pH. Proteins on the cell wall of the bacterium affinity-purified using invertase as a ligand were identified to be heat shock proteins such as DnaK and GroEL and glycolytic enzymes such as pyruvate kinase and glyceraldehyde-3-phosphate dehydrogenase. DnaK bound to both the bacterium and yeast at pH 4 and aggregated them at above 0.1 mg/ml, whereas no significant difference between the circular dichroism spectra of DnaK at pH 4 and 7 was observed. These results indicate that the cytosolic proteins, including DnaK displayed on the cell wall, cause the lactic acid bacterium to adhere to the yeast.
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PMID:Lactic acid bacteria display on the cell surface cytosolic proteins that recognize yeast mannan. 1989 42

Leaves on transgenic tobacco plants expressing yeast-derived invertase in the apoplast develop clearly demarcated green and bleached sectors when they mature. The green areas contain low levels of soluble sugars and starch which are turned over on a daily basis, and have high rates of photosynthesis and low rates of respiration. The pale areas accumulate carbohydrate, photosynthesis is inhibited, and respiration increases. This provides a model system to investigate the "sink" regulation of photosynthetic metabolism by accumulating carbohydrate. The inhibition of photosynthesis is accompanied by a decrease of ribulose-1,5-bisphosphate and glycerate-3-phosphate, and an increase of triosephosphate and fructose-1,6-bisphosphate. The extracted activities of ribulose-1,5-bisphosphate carboxylase, fructose-1, 6-bisphosphatase and NADP-glyeraldehyde-3-phosphate dehydrogenase decreased. The activity of sucrose-phosphate synthase remained high or increased, an increased portion of the photosynthate was partitioned into soluble sugars rather than starch, and the pale areas showed few or no oscillations during transitions between darkness and saturating light in saturating CO2. The increased rate of respiration was accompanied by an increased level of hexose-phosphates, triose-phosphates and fructose-1,6-bisphosphate while glycerate-3-phosphate and phosphoenolpyruvate decreased and pyruvate increased. The activities of pyruvate kinase, phosphofructokinase and pyrophosphate: fructose-6-phosphate phosphotransferase increased two- to four-fold. We conclude that an increased level of carbohydrate leads to a decreased level of Calvin-cycle enzymes and, thence, to an inhibition of photosynthesis. It also leads to an increased level of glycolytic enzymes and, thence, to a stimulation of respiration. These changes of enzymes are more important in middle- or long-term adjustments to high carbohydrate levels in the leaf than fine regulation due to depletion of inorganic phosphate or high levels of phosphorylated metabolites.
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PMID:"Sink" regulation of photosynthetic metabolism in transgenic tobacco plants expressing yeast invertase in their cell wall involves a decrease of the Calvin-cycle enzymes and an increase of glycolytic enzymes. 2419 31


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