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 effect of undernutrition on rat small intestine during the critical newborn period was studied. A severe state of protein-energy malnutrition was induced by litter expansion which caused the mean total body weight of experimentally malnourished rats to diminish significantly as compared to control animals. Intestinal weight and total DNA were similarly diminished in the malnourished rats. DNA and protein expressed per gram wet tissue showed no significant differences between groups. Retarded intestinal growth in the malnourished animals was the result of reduced cell number. The mean specific activities of sucrase and maltase were diminished in the experimental group, with mean activities being 20 to 50% of controls, respectively. These differences were larger when expressed as total organ activities. On the other hand, specific lactase activity was significantly higher in undernourished rats but total lactase activity per organ was similar in both groups. Enterokinase specific activity or total organ activity was significantly higher in the undernourished rats.
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PMID:The effect of early postnatal acquired malnutrition on intestinal growth, disaccharidases and enterokinase. 11 73

Isoelectrofocusing of abdominal extracts of Drosophila melanogaster revealed the existence of two forms of sucrase (E.C. 3.2.1.26). One form exhibited an isoelectric point of 4.63 +/- 0.02 while the other form exhibited an isoelectric point of 4.83 +/- 0.02. The localization of the structural gene for sucrase is proposed on the basis of enzyme determinations in a series of duplication- and deletion-bearing aneuploids. We suggest that the sucrase structural gene lies between 31CD and 31EF on the left arm of chromosome 2 and that the two forms of abdominal sucrase derive from a common protein coded for by a single sucrase gene designated Sucr+.
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PMID:Genetic and biochemical aspects of sucrase from Drosophila melanogaster. 12 Jan 95

In order to investigate the relationship between dietary amino acids and protein, as well as the activities of intestinal sucrase and leucine aminopeptidase in rats, the effects of an amino acid imbalance on these enzyme activities were studied. The amino acid imbalance was created by adding 8% of an indispensable amino acid mixture lacking threonine to a 6% casein diet supplemented with 0.3% methionine. The food intake and growth of rats fed the imbalanced diet ad libitum were depressed, and the segmental weights of the small intestine and its sucrase activity were clearly lower than those of rats fed the basal diet. The effect of the imbalanced diet under pair-feeding condition on the sucrase activity was similar to that under an ad libitum feeding condition. The food intake and segmental sucrase activity, that is, sucrase activity per length of the small intestine, of rats injected with cortisol (1 mg/day) and fed the imbalanced diet were not depressed, although administration of insulin (1.5 U/day) had no effect on the food intake or segmental sucrase activity. Force-feeding stimulated growth of rats receiving the imbalanced diet, as well as increasing their segmental sucrase activities. The effects of these different conditions on the leucine aminopeptidase activity of rats receiving the imbalanced diet were obscure. These results suggest that changes in segmental sucrase activity might be mediated by stimulating factors in food intake affected by the composition of ingested amino acids and protein together with sucrose in the gastrointestinal lumen.
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PMID:Effect of an amino acid imbalance on intestinal sucrase and leucine aminopeptidase activities in rats. 12 Apr 27

Experimental diabetes alters intestinal mucosal function in a variety of ways including the enhancement of both active transport processes and the activity of brush-border hydrolases. These effects could result from changes in either intraluminal factors (food, bile, pancreatic enzymes) or extraluminal factors (blood flow, hormones, nervous impulses). To determine the role of intraluminal factors we studied the effect of diabetes on segments of jejunum completely excluded from luminal continuity, but with intact blood and nerve supply. Three weeks after construction of Thiry-Vella fistulas in rats, diabetes was induced with streptozotocin. Five days later sucrase activity was measured in both the excluded segment and in the proximal jejunum. Exclusion alone resulted in a 77 per cent decrease in mucosal protein content with no change in sucrase specific activity suggesting simply a diminished number of mucosal cells. Diabetes increased the specific activity of sucrase from 0.0643 mumoles per minute per milligram of protein plus or minus 0.0077 (SEM) to 0.1074 plus or minus 0.0182 (P smaller than 0.05) in the proximal jejunum and from 0.0467 plus or minus 0.0047 to 0.1040 plus or minus 0.0191 (P smaller than 0.02) in the excluded segment. These results provide conclusive evidence that the diabetic enhancement of sucrase activity is independent of intraluminal factors and must be the consequence of extraluminal changes.
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PMID:Enhancement of intestinal sucrase activity in experimental diabetes: the role of intraluminal factors. 12 49

The effects of deoxycholate, taurocholate and cholate on transport and mucosal ATPase activity have been investigated in the rat jejunum in vivo using closed-loop and perfusion techniques. In the closed-loops, 5 mM deoxycholate selectively inactivated (Na+ + K+)-ATPase, and net secretion of Na+ induced by 2.5 mM deoxycholate was due to reduced lumen to plasma flux of the ion; deoxycholate (2.5 mM) produced marked inhibition of 3-0-methylglucose transport. Luminal disappearance rates of deoxycholate (60.5 plus or minus 2.9% per g wet st of gut) greatly exceeded those of taurocholate (4.3 plus or minus 1.0). In the perfusion studies 1 mM deoxycholate induced net secretion of water, Na+ and C1-, and inhibited active glucose transport; concomitantly "total" ATPase, (Na+ + K+)-ATPase, and Mg-2+-ATPase were inhibited. At higher concentrations (5 mM) deoxycholate stimulated Mg-2+-ATPase activity. Taurocholate and cholate at 1mM had no effect on transport of (Na+ + K+)-ATPase. Mucosal lactase, sucrase and maltase activities were not affected by 1 mM deoxycholate, taurocholate or cholate. These results suggest that deoxycholate inhibits sodium-coupled glucose transport by inhibition of (Na+ + K+)-ATPase at the lateral and basal membranes of the epithelial cell, rather than from an effect at the brush-border membrane level.
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PMID:A comparative study on the effects of different bile salts on mucosal ATPase and transport in the rat jejunum in vivo. 12 87

Specific and total activities of lactase, sucrase and maltase were determined in the mucosa scraped from the proximal, mid and distal intestinal segments of nonpregnant and pregnant normal control and diabetic rats. In control rats, pregnancy was accompanied by a significant rise in total lactase activity of the entire intestinal mucosa. This was due to increased specific activity of the enzyme in the mid segment of the pregnant rats. In both nonpregnant and pregnant rats, diabetes was associated with marked enhancement of intestinal growth and with elevated specific and total activities of the three mucosal disaccharidases. In the pregnant diabetic rats, specific and total activities of the disaccharidases were about 30% lower than corresponding values in the nonpregnant diabetic rats.
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PMID:Intestinal disaccharidases in the rat: effects of pregnancy and diabetes. 13 Apr 71

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

As enterocytes migrate from crypts to villi they differentiate and mature. To examine the effect of epithelial differentiation on ion transport we studied 22Na+ efflux and (Na+--K+)-adenosine triphosphatase activity in suspensions of epithelial cells selectively isolated from different regions of the villus to compare crypt cells with villous tip cells. Enterocytes were isolated from rat jejunum by a dilation-vibration technique. Thymidine kinase, sucrase, and alkaline phosphatase activities were measured as markers of specific cell populations. Compared to villous cells, cells from the crypt region demonstrated lower (Na"--K+)-adenosine triphosphatase activity, lower total and passive Na+ efflux rate constants, and failure of Na+ transport to respond to an actively transported nonelectrolyte.
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PMID:Na+ transport in jejunal crypt cells. 13 28

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

Brush border sucrase and lactase activities are significantly elevated in alloxan-induced chronic diabetes and are restored to control levels after insulin treatment. Alkaline phosphatase and Mg-ATPase levels remain unchanged in diabetes, compared to a control group. Insulin treatment alone to control animals also led to enhanced activities of these enzymes.
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PMID:Effect of chronic alloxan diabetes and insulin administration on intestinal brush border enzymes. 14 19


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