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)

Intestinal mucosa from 40 patients obtained by fiber-endoscopic biopsy was assayed for disaccharidases to determine suitability of this tissue for assay. The combined specimens from each patient provided 4.7-38.7 mg of tissue, adequate in all instances for duplicate determinations of protein, lactase, sucrase, and maltase. Tissue remained for assays of palatinase in 39 instances, trehalase and cellobiase in 37, and alkaline phosphatase in 22 cases. Twenty-four subjects had normal lactose tolerance tests and normal sucrase/lactase ratios. Thirteen patients with abnormal oral lactose tolerance tests were identified as having a primary low lactase activity on the basis of elevated sucrase/lactase ratios. This ratio was most helpful in making the diagnosis of a primary low lactase, since the mucosal specimens were not obtained from comparable areas. Tissue from three subjects with an abnormally low maltase was unsuitable for diagnosis. Endoscopic biopsy of mucosa appears to be satisfactory for disaccharidase assays in most instances.
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PMID:Adequacy of endoscopic biopsy specimens for disaccharidase assays. 10 20

This study was undertaken to investigate the effect of alcohol on the activity of jejunal disaccharidases (DS). The activity of DS in a preparation of purified brush border membrane of hamster jejunum was measured in the absence and in the presence (0.8 to 6.4% wt/vol) of ethanol. To compare the effect of alcohol on DS with its action on a brush border enzyme of a different group, we also measured the activity of alkaline phosphatase (AP) under similar conditions. Ethanol depressed the activity of sucrase, maltase, and lactase in a dose-dependent and time-dependent manner, but it stimulated the activity of AP. The ethanol-induced inhibition of DS was completely reversible. Kinetic studies indicate that ethanol depressed the Vmax and increased the Km of sucrase and lactase. The Vmax of maltase also decreased, but the Km of this hydrolase was not affected by ethanol. From the results of this study it would appear that acute exposure of the jejunal brush border to ethanol depresses the DS activity of the membrane and that (because the AP was not depressed) the ethanol-induced inhibition of DS is not the result of a general inhibition of all enzymes of the brush border.
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PMID:Effect of ethanol on disaccharidases of hamster jejunal brush border membrane. 11 61

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

Differential centrifugation of rat small intestinal homogenates produced a crude brush border (BB) fraction that was enriched 15-fold for the marker enzymes, alkaline phosphatase and sucrase; contamination with mitochondrial enzymes, monoamine oxidase and succinate dehydrogenase, was minimal. ATP hydrolysis by this BB fraction was stimulated by addition of several anions to the incubation medium: HCO3 and Cl were equally effective in this regard, with NO3, NO2, SO4, and acetate being less stimulatory. SCN and CNO inhibited ATPase activity, whereas the divalent anion SO3 was stimulatory at low concentrations (less than 25 mM) but inhibitory at 100 mM. Maximum anion stimulation was observed at a Mg concentration of 0.5 mM, and pH optimum was 8.5. Kinetic analysis showed that HCO3 increased the Vmax without altering the Km for ATP; the Ka for this effect of HCO3 was 35 mM. This enzyme activity was completely inhibited by 20 mM L-phenylalanine, 10 mM L-cysteine, and 3 mM EDTA, compounds that also inhibited intestinal alkaline phosphatase. These results demonstrate the presence of anion-stimulated ATPase activity in rat small intestinal brush border and suggest that this activity may be related to intestinal alkaline phosphatase. The role of this enzyme in intestinal transport is not known, but could relate to the regulation of intestinal absorption and secretion.
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PMID:Anion-stimulated ATPase activity of brush border from rat small intestine. 15 3

The subcellular distribution of adenyl cyclase was investigated in small intestinal epithelial cells. Enterocytes were isolated, disrupted and the resulting membranes fractionated by differential and sucrose gradient centrifugation. Separation of luminal (brush border) and contra-luminal (basolateral) plasma membrane was achieved on a discontinuous sucrose gradient. The activity of adenyl cyclase was followed during fractionation in relation to other enzymes, notably those considered as markers for luminal and contraluminal plasma membrane. The luminal membrane was identified by the membrane-bound enzymes sucrase and alkaline phosphatase and the basolateral region by (Na+ + K+)-ATPase. Enrichment of the former two enzymes in purified luminal plasma membrane was 8-fold over cells and that of (Na+ + K+)-ATPase in purified bisolateral plasma membranes was 13-fold. F--activated adenyl cyclase co-purified with (Na+ + K+)-ATPase, suggesting a common localization on the plasma membrane. The distribution of K+-stimulated phosphatase and 5'-nucleotidase also followed (Na+ + K+)-ATPase during fractionation.
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PMID:The surface membrane of the small intestinal epithelial cell. I. Localization of adenyl cyclase. 17 91

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

The rat small bowel was perfused in vivo and ex vivo in the absence of biliary and pancreatic secretion. Intraluminal release of sucrase, alkaline phosphatase, aminopeptidases and enterokinase was significantly increased after administration of pentagastrin, caerulein and glucagon at doses ranging between 1 pg and 10 microgram. This suggests that there is a direct hormonal stimulation of the intestinal mucosa. This effect might at least partly be mediated through cyclic AMP since dibutyryl derivates of this cyclic nucleotide exerted a significant stimulatory effect on intraluminal release of proteins, sucrase and enterokinase, although the pattern of enzyme was quite different from the effect produced by the three peptides.
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PMID:Hormonal stimulation of intestinal brush border enzymes release. 20 30

The postition of a number of human intestine brush border membrane enzyme activities in polyacrylamide gels after electrophoresis has been determined. These activities are, in order from the origin, maltase/glucoamylase, lactase/phlorizin hydrolase, maltase/sucrase/isomaltase, enteropeptidase, trehalase and gamma-glutamyl-transferase. Leucylnaphthylamide hydrolyzing activity was inactivated by sodium dodecylsulfate and its position was not determined. The positions of the activities have been correlated with the positions of protein bands previously determined. One such band situated between enteropeptidase and alkaline phosphatase has not been identified.
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PMID:Enzymes of the human intestinal brush border membrane. Identification after gel electrophoretic separation. 23 25

The activities of rat intestinal enzymes, sucrase, lactase, maltase, trehalase, gamma-glutamyltransferase, leucylnaphthylamide-hydrolyzing activity, and the transport system for glucose follow diurnal rhythms on ad libitum and restricted feeding regimes. In response to 6 days of restricted feeding, food available between 1400 and 1800 Eastern Standard Time, all rhythms shifted in time and the daily levels of activities were changed. Alkaline phosphatase activity followed a diurnal rhythm only in restricted fed animals. In restricted fed rats several activity patterns were observed, some with short periods of maximum activity, 3 h or less, and some with plateaus of maximum activity, 5-9 h long. In respect to the time of day of the synchronizer, sucrase peaked before feeding, glucose transport peaked during feeding, alkaline phosphatase peaked after feeding, and the other enzymes had higher levels of activity before, during and after feeding. The effect of restricted feeding on the daily activity levels were: a decrease in leucylnaphthylamide-hydrolyzing activity, no change in alkaline phosphatase, and increases in the others. These enzyme and transport systems exhibit a large amount of individual regulation or control as reflected by the lack of a uniform activity pattern and response to the synchronizer, and the variation in direction and magnitude of the adaptations to restricted feeding.
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PMID:Effect of changes in feeding schedule on the diurnal rhythms and daily activity levels of intestinal brush border enzymes and transport systems. 24 Apr 40

The effects of corticosteroid have been studied in rats submitted to oral administration of prednisone (5 mg. per kg. per day) during 8, 15, 30, and 90 days. The results were compared to those obtained after parenteral administration of hydrocortisone acetate (50 mg. per kg. per day intramuscularly). The morphometric changes of the villus-crypt axis and the brush border enzymic content of the mucosa (sucrase, enterokinase, alkaline phosphatase, and aminopeptidase) were the parameters investigated at the duodenal, jejunal, and ileal levels. Oral administration of prednisone resulted in a significant increase of the duodenal villous height at the 15th (+ 13 per cent, p less than 0.01), 30th (+ 33 per cent, p less than 0.001), and 90th day (+ 56 per cent, p less than 0.001), whereas in the jejunum a constant decrease of the villous height was noted. Parenteral hydrocortisone administration did not affect intestinal morphology. Effects of oral corticosteroids on the microvillous enzymic activities were related to both intestinal level and duration of corticoids administration: (1) in the duodenum increase of sucrase, alkaline phosphatase, and aminopeptidase during 30 days followed by normalization at the 90th day, (2) an initial increase of sucrase, alkaline phosphatase, and aminopeptidase limited to the first 8 days in the jejunum, and (3) a significant rise of alkaline phosphatase (greater than 100 per cent, p less than 0.001) and enterokinase (greater than 100 per cent, p less than 0.001) in the ileum at the 15th day of treatment. Parenteral corticosteroid administration was associated with a significant increase of both sucrase and enterokinase activities. The present study suggests that: (1) Corticosteroids exert a direct effect on the intestinal morphology varying with the intestinal level and duration of treatment. (2) No correlation could be established between anatomic and functional changes. (3) Oral corticosteroids exert an enhancing effect of the brush border enzymic activities, even in the adult mucosa and particularly at the ileal level where they stimulate significantly the enterokinase mucosal activity. (4) Parenteral corticosteroids exert a more specific effect limited to sucrase and enterokinase enhancement.
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PMID:Effects of oral and parenteral corticosteroids on intestinal villous morphology and brush border enzymes in the rat. 31 75


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