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)

The initial step of disaccharide dissimilation by Actinomyces viscosus serotype 2 strain M-100 was studied. Sucrase activity was found in the 3,000 X g particulate fraction and the 37,000 X g soluble fraction of the cells, whereas lactase activity was found almost exclusively in the 37,000 X g soluble fraction. Neither sucrase nor lactase activity was appreciable in the culture liquor. Sucrose phosphorylase, alpha-glucosidase, and polysaccharide synthesis activities were not observed in the soluble cell fraction. The sucrase was identified as invertase (EC 3.2.1.26; beta-D-fructofuranoside fructohydrolase). The lactase was identified as beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase). The enzymes in the 37,000 X g soluble fraction were separable by diethylamino-ethyl-cellulose chromatography, giving one beta-galactosidase peak and one major and one minor invertase peak. Acrylamide gel electrophoresis showed different electrophoretic mobilities of the enzymes. The molecular weight of the beta-galactosidase is about 4.2 X 10(5) and that of invertase is about 8.6 X 10(4). The beta-galactosidase has a Km for lactose of about 6 mM and a pH optimum between pH 6.0 and 6.5. The major invertase component has a Km for sucrose of about 71 mM and a pH optimum between pH 5.8 and 6.3.
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PMID:Identification, separation, and preliminary characterization of invertase and beta-galactosidase in Actinomyces viscosus. 1 74

Purified sucrase-isomaltase complex sucrose alpha-glucohydrolase, EC 3.2.1.48 - dextrin 6-alpha-glycanohydrolase, EC 3.2.1.10) solubilized by papain from rabbit intestine was dissociated by citraconylation into its subunits, sucrase and isomaltase, which were then isolated in a form active immunologically as well as enzymatically by affinity chromatography on Sephadex G-200 and gel-filtration on Bio-gel P-300. Antibodies against the purified complex inhibited isomaltase but not sucrase and formed precipitation lines, crossing each other, with isolated sucrase and isomaltase, showing that the two enzymes differ in antigenicity from each other. By absorbing the antibodies with isolated sucrase and isomaltase, antibodies specific for isomaltase and sucrase, respectively, were obtained. Like the original antibodies, both of the specific antibodies quantitatively agglutinated microvillous vesicles. Sucrase was inhibited by neither of the antibodies. In contrast, isomaltase was greatly inhibited by the isomaltase-specific antibodies, but not by the sucrase-specific ones.
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PMID:Immunochemical studies on the subunits of rabbit-intestinal sucrase-isomaltase complex. 7 Feb 24

Jejunal and ileal segments from preterm rat fetuses were implanted under the kidney capsula of adult rats. Sucrase, lactase and acid beta-galactosidase activities were determined in the isografts at different times after implantation, and in corresponding segments developing in situ. Whereas fetal intestine contains considerable activity of acid beta-galactosidase and lactase, no sucrase activity is detectable. Similarly -- as in situ -- 4 weeks after the implantation the jejunal segment exhibited higher activity of sucrase and lactase than the ileal segment. Acid beta-galactosidase was more active in ileal than in jejunal segments -- both growing in situ as well as isografts. Experiments have thus demonstrated that the expression of the jejunoileal gradient of activity of the 3 enzymes studied does not depend on direct contact with food or gastric, pancreatic and biliary juices. This gives validity to the suggestion that the gradient may already be programmed in fetal intestinal tissue, but other factors active in situ might be responsible for its magnitude.
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PMID:Development of jejunoileal differences of activity of lactase, sucrase and acid beta-galactosidase in isografts of fetal rat intestine. 11 41

A procedure was developed for the analytical isolation of brush border and basal lateral plasma membranes of intestinal epithelial cells. Brush border fragments were collected by low speed centrifugation, disrupted in hypertonic sorbitol, and subjected to density gradient centrifugation for separation of plasma membranes from nuclei and core material. Sucrase specific activity in the purified brush border plasma membranes was increased fortyfold with respect to the initial homogenate. Basal lateral membrane were harvested from the low speed supernatant and resolved from other subcellular components by equilibrium density gradient centrifugation. Recovery of Na, K-ATPase activity was 94%, and 61% of the recovered activity was present in a single symmetrical peak. The specific activity of Na, K-ATPase was increased twelvefold, and it was purified with respect to sucrase, succinic dehydrogenase, NADPH-cytochrome c reductase, nonspecific esterase, beta-glucuronidase, DNA, and RNA. The observed purification factors are comparable to results reported for other purification procedures, and the yield of Na, K-ATPase is greater by a factor of two than those reported for other procedures which produce no net increase in the Na, K-ATPase activity. Na, K-ATPase rich membranes are shown to originate from the basal lateral plasma membranes by the patterns of labeling that were produced when either isolated cells or everted gut sacs were incubated with the slowly permeating reagent 35S-p-(diazonium)-benzenesulfonic acid. In the former case subsequently purified Na, K-ATPase rich and sucrase rich membranes are labeled to the same extent, while in the latter there is a tenfold excess of label in the sucrase rich membranes. The plasma membrane fractions were in both cases more heavily labeled than intracellular protein. Alkaline phosphatase and calcium-stimulated ATPase were present at comparable levels on the two aspects of the epithelial cell plasma membrane, and 25% of the acid phosphatase activity was present on the basal lateral membrane, while it was absent from the brush border membrane. Less than 6% of the total Na, K-ATPase was present in brush border membranes.
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PMID:Analytical isolation of plasma membranes of intestinal epithelial cells: identification of Na, K-ATPase rich membranes and the distribution of enzyme activities. 13 16

Diabetes stimulates the functional activity of the intestinal brush border membrane with enhancement of both hydrolytic enzyme activity and membrane transport systems. To determine the mechanism of this effect, we studied the effects of streptozotocin diabetes on the metabolism of one membrane protein, sucrase-isomaltase, which increases its activity in diabetes. The protein was purified and an antiserum prepared. Sucrase-isomaltase from control and diabetic rats was immunologically identical as shown by Ouchterlony double-diffusion analysis of papain-solubilized mucosal proteins. The increase in sucrase enzyme activity in diabetic animals (31.0+/-1.4 U SEM 5 days after streptozotocin vs. 13.1+/-1.0 in controls) was the consequence of increased enzyme protein and not an alteration in catalytic efficiency as demonstrated by quantitative immunoprecipitin reactions. To account for increased sucrase-isomaltase protein in diabetes we studied papain-solubilized mucosal proteins labeled by injection of [(14)C]carbonate and [(14)C]leucine and analyzed incorporation into sucrase-isomaltase protein (anti-serum precipitable) and total protein (trichloroacetic acid precipitable). We found that diabetes did not affect the decay of labeled total protein, but prolonged the decay of labeled sucrase-isomaltase. t((1/2)) of sucrase-isomaltase was 4.4 h in control animals after [(14)C]carbonate injection and 8.8 and 10.2 h, respectively, 2 and 5 days after induction of streptozotocin diabetes. We obtained similar results in experiments with [(14)C]leucine with diabetes increasing t((1/2)) from 6 to 13.6 h. Diabetes did not appear to increase the rate of addition of sucrase-isomaltase to the brush border membrane, since it did not affect the 10- and 60-min incorporations of isotope into sucrase-isomaltase protein relative to incorporation into total protein and did not alter rate constants for synthesis calculated from the t((1/2)) and the change in enzyme mass over time.Thus, enhanced sucrase activity in the diabetic animal is the consequence of an increase in sucrase-isomaltase protein which develops because of a decrease in its rate of degradation.
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PMID:The intestinal brush border membrane in diabetes. Studies of sucrase-isomaltase metabolism in rats with streptozotocin diabetes. 14 62

Recent studies have demonstrated that the human intestinal enzymes of carbohydrate digestion and metabolism can be regulated by dietary sugars. These studies have utilized direct assay of intestinal mucosal enzyme activity. Mucosa has been obtained by the use of peroral jejunal biopsy techniques which provide 10-15 mg of mucosa in a safe, simple and reproducible manner. Dietary sucrose, as compared to dietary glucose, increases the activities of the jejunal disaccharidases, sucrase and maltase, but not lactase. Fructose reproduces the sucrose effect and appears to be the active principle in the sucrose molecule. Lactose deprivation or lactose feeding does not alter lactase activity. Fructose has been useful in treating one patient with sucrase-isomaltase deficiency. Jejunal glycolytic enzyme activities are also regulated by dietary sugars. Certain enzymes are highest with specific dietary carbohydrates, lower with other sugars and lowest on a carbohydrate-free diet. The regulation of human jejunal glycolytic enzyme activity takes place in hours, whereas the change in disaccharidase activity occurs in 2-5 days. The mechanism of this regulation is not known. Additional investigations have shown that jejunal glycolytic enzyme activities but not the disaccharidases are controlled by oral folic acid as well. This effect occurs within 1 day also. The mechanism is unknown. Large doses of folate have been of benefit in a few patients with certain glycolytic enzyme deficiency states. Preliminary studies have demonstrated that selected patients with chronic undiagnosed intestinal disorders fail to manifest an adaptive response of their jejunal glycolytic enzyme activities to dietary sugars. This condition has been termed a "maladaptation syndrome.".
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PMID:Diet and intestinal enzyme adaptation: implications for gastrointestinal disorders. 16 4

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

1. Jejunal biopsy specimens from three children with congenital sucrase-isomaltase deficiency were assayed for disaccharidase activity and were subjected to analytical subcellular fractionation with enzymic microanalysis. 2. By use of the highly sensitive fluorigenic modification of the disaccharidase assay, brush-border sucrase and isomaltase activities were depressed but nevertheless detectable in each child. 3. Apart from the expected decrease in brush-border alpha-glucosidase activity, the other enterocyte marker-enzyme activities were normal. 4. There were no abnormalities in the enterocytes of any child on analytical subcellular fractionation or on electron microsocopy.
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PMID:Subcellular fractionation studies of the intestinal mucosa in congenital sucrase--isomaltase deficiency. 38 73

The cellular changes that take place as the intestinal cell migrates from crypt to villus are morphologically and biochemically remarkable. It is fortunate that many of these phenomena can be delineated by following enzymic activities. Sucrase-isomaltase is a particularly fascinating enzyme complex because it is a marker of the differentiated cell. Sucrase is inducible with steroids and protected by the substrate sucrose. Purified enzyme can be used to stimulate production of specific antibodies in goats; these antibodies have been used as probes to locate enzymically active and inactive antigen in the cells of the crypt and villus respectively. Further examination of the enzyme has indicated a molecular weight of 200 000--350 000. These higher molecular weight components are located in the brush border of the enterocytes. Lower molecular weight subunits are antigenically active and are in the cytosol. It is assumed that these smaller components are enzymically inactive pre-combination subunits of the sucrase-isomaltase complex and that the sucrase-isomaltase of the brush border is an aggregate of these subunits. The California sea lion, which is deficient in intestinal sucrase activity, does have isomaltase activity. This finding supports the concept that there are different gene complexes for sucrase and for isomaltase.
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PMID:Sucrase and cellular development. 39 32

In a child with hereditary sucrase-isomaltase deficiency immunoreactive enzyme was present in the intact duodenal mucosa. Polyacrylamide gel electrophoresis carried out with membrane fragments of an intestinal biopsy showed an abnormal protein band without enzyme activity. The mucosa had a relatively high residual isomaltase activity which was recovered from the gel in a position suggesting higher than normal molecular weight. The results indicated that in this patient the primary structural defect was in the sucrase moiety which was enzymatically inactive. The isomaltase subunits may have aggregated into a large molecular weight complex because of unavailability of their partners. The observation also provided evidence for separate biosynthesis of the two moieties of the sucrase-isomaltase complex.
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PMID:The brush border membrane in hereditary sucrase-isomaltase deficiency: abnormal protein pattern and presence of immunoreactive enzyme. 41 77


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