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)

Starvation overnight and starvation for 48 h reduced the weight and the protein content of mucosal scrapings, but only minimally reduced the DNA content of the mucosal scrapings. The activity of sucrase and maltase was reduced by both periods of starvation. The activity of lactase and of acid and alkaline phosphatase, however, was less subject to starvation. There were striking differences in the response to starvation between the proximal, mid and distal third of the small intestine. The importance of the proper reference system was discussed.
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PMID:Effect of starvation on small intestinal enzyme activity in germ-free rats. 10 66

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

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

Saccharomyces cerevisiae -136ts synthesized invertase in media containing maltose and sucrose. In the presence of glucose synthesis of enzyme took place when the sugar concentration was lower than 1%. At higher concentrations enzyme formation was repressed. Analysis of the glucose effect before RNA inhibition showed that the hexose interfered with the transcription of DNA into invertase messenger RNA. Translation of invertase messenger already formed was also inhibited and the kinetics of this effect was similar to that produced by cycloheximide. Invertase activity was independent of glucose suggesting that the hexose produces no catabolite inhibition of invertase activity. Inhibition of invertase translation by glucose turned out to be reversible but the amount of enzyme produced was dependent on duration of treatment. It is suggested that the catabolite repression of invertase synthesis produced by glucose operates at the levels of transcription and translation and produces an increase in the rate of mRNA degradation. The catabolite repression has no effect on secretion and does not interfere with the catalytic activity of invertase.
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PMID:The mechanism of catabolite inhibition of invertase by glucose in Saccharomyces cerevisiae. 32 Oct 21

Saccharomyces cerevisiae -136ts (Hutchison, H.T., Hartwell, L.H. and McLaughlin, C.S. (1969) J. Bacteriol. 99, 807-814) incubated in the presence of maltose at 23 degrees C (permissive temperature) synthesized the RNA messengers which codify derepressed invertase (an external mannoprotein) and induced alpha-glucosidase (a non-glycosylated internal enzyme). The enzymes were not synthesized if the mutant was transferred to the maltose-containing medium at the moment of incubation at 37 degrees C indicating that the cells had no pools of the specific RNA messengers and that transcription of the DNA was a prerequisite to enzyme synthesis. Cycloheximide inhibited syntheses of the enzymes both at 37 and at 23 degrees C suggesting that the enzymic activities were the result of "de novo" synthesis of the proteins and did not result from the activation of proenzymes. In derepressed cells the number of invertase mRNA molecules is probably larger than that actually being translated. The half-life of the derepressed invertase mRNA was calculated from the moment that the molecules of RNA messenger were limiting the enzyme synthesis and a value of 30-35 min was estimated. The value found for the basal (repression independent) invertase mRNA was of 45-50 min. The half-life of alpha-glucosidase mRNA was computed following the mathematical procedure described in the Appendix, and a value of 23 min was obtained. These results are consistent with the existence of relatively long-lived RNA messengers involved in the synthesis of extracellular macromolecules.
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PMID:Invertase messenger ribonucleic acid in Saccharomyces cerevisiae. Kinetics of formation and decay. 32 19

Intravenous administration of 1 U cholecystokinin-pancreozymin (CCK-PZ) to rats caused the release of enteropeptidase, alkaline phosphatase (AP), and sucrase to the intestinal lumen in the absence of a concomitant increase in luminal DNA. Thus, the hormone elicited hydrolase secretion was not due to cell desquamation. Pentagastrin also stimulated hydrolase release. Following CCK-PZ administration enteropeptidase was released preferentially over sucrase and AP and showed a linear correlation with total protein output. The specific enteropeptidase activity was higher in the perfusate following secretion than in the mocosa. Enteropeptidase was found mainly in soluble form in both mucosa and perfusate; addition of bile following enteropeptidase release further increased its activity. In contrast, sucrase and AP were found mainly in insoluble form in both mucosa and perfusate and their specific activities were higher in the mucosa. The presence of bile rendered both sucrase and AP more soluble in the perfusate. The data indicate that enteropeptidase is released by a specific secretory process and that its subcellular site of origin is different from that of sucrase and AP. By eliciting the coordinated release of trypsinogen, enteropeptidase and bile, CCK-PZ plays a central role in the initiation of protein digestion.
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PMID:Studies on intestinal enzyme secretion; the action of cholecystokinin-pancreozymin, pentagastrin and bile. 68 84

The functional and structural characteristics of the ileal remnant of rat intestine were examined four weeks after 45%, 70% or 95% proximal resection. The increase in villus height in the ileal remnant had alfread reached its maximum after a resection of 45%, whereas a further increment in the length of the crypts occurred after 70% resection. There was an increase in the number of enterocytes per unit length of villus and a rise in the DNA content per unit weight of mucosal scrapings, which testifies to the development of mucosal hyperplasia in this situation. The specific activities of sucrase, measured biochemically, and of nonspecific esterase, determined histochemically, were reduced in proportion to the extent of the resection. Similarly, the uptakes of L-phenylalanine and of beta-methyl-D-glucoside by intestinal rings in vitro were progressively diminished in the ileal remnant. There was an increase in the rate of disappearance of glucose from a perfused loop in vivo, when expressed in terms of unit intestinal length. Galactose absorption remained unchanged, but when expressed in terms of unit dry tissue, was significantly reduced, in agreement with the diminished transport of both amino-acids and monosaccharides in vitro.
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PMID:The relationship between the functional and structural alterations in the rat small intestine following proximal resection of varying extents. 68 86

Starvation for 48 hrs reduced the activity of sucrase referred to unit length in rat proximal small intestine by approximately 30%, irrespective of whe her mucosal scrapings, isolated villus epithelial cells or brush border membranes were investigated. Sucrase activity referred to unit weight, unit protein or to unit DNA of intestinal epithelium did not change.
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PMID:Starvation and sucrose activity in small intestinal mucosa. An evaluation of different tissue preparations and reference systems. 68 56

Although intraluminal nutrition presumably maintains small intestinal mass by direct contact with the epithelial cells, hormonal or neurovascular elicited by feeding may play an indirect role. In order to test for the presence of indirect factors, Thiry- Vella fistulae were created from the proximal small intestine of two groups of rats. The bypassed gut of a group of rats receiving an elemental diet intravenously was compared to a second group receiving the same diet by intragastric infusion. After 1 week, there was significantly greater (P less than 0.01) gut weight, mucosal weight, DNA content, and protein content of both the gut in continuity and tje bypassed gut of intragastric infused rats. Total sucrase activity was also greater (P less than 0.01) in intragastric fed rats, and this was due to both a greater protein content and specific activity (P is less than 0.05) of the gut in continuity and to the greater protein content of the bypassed gut. Serum gastrin levels were similar (P less than 0.05) in both groups, suggesting that gastrin may not play a role in initiating the differences reported. This study suggests that intraluminal nutrition maintains the small intestinal epithelial population in part, indirectly, by unidentified hormonal or neurovascular stimuli.
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PMID:Small intestinal mass of the rat is partially determined by indirect effects of intraluminal nutrition. 82 8

The effects of carbohydrate intake on jejunal disaccharidases in rats with chronic mannitol-induced, osmotic diarrhea were studied. Weanling rats were force-fed 5 ml/100 g of body weight of water of 20% mannitol (w/v 1300 mOsm) daily for up to 14 days. Diets containing 70% of either starch, sucrose, glucose, or 20% lactose with 50% starch were fed ad libitum. Mannitol-fed rats had increased water intake and diarrhea. They gained weight, but less than controls. The levels of intestinal disaccharidases in mannitol-fed rats were related to dietary carbohydrate intake. Seven days of mannitol treatment led to lactase and sucrase deficiencies in rats fed starch whereas jejunal maltase and alkaline phosphatase were unchanged. Deficiencies in lactase and maltase but not in sucrase were induced when rats were fed a sucrose diet, while a decrease only in sucrase occurred in rats fed a lactose-starch diet. Rats with mannitol-induced diarrhea fed a glucose diet had reduced levels of all disaccharidases. The changes in intestinal disaccharidases were not associated with alterations in the number of epithelial cells or ultrastructural abnormalities. 3H-thymidine incorporation into DNA following 7 days of mannitol treatment was similar to water-fed controls. Absorptive epithelial cells were not damaged and the microvilli were normal in height and appearance. These data suggest that the levels of specific disaccharidases show and enhanced dependence upon the corresponding dietary substrates during diarrhea induced by an osmotic load.
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PMID:Interaction between dietary carbohydrates and intestinal disaccharidases in experimental diarrhea. 85 Oct 74


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