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)

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

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

A genetically conditioned mouse model of exocrine pancreatic insufficiency (epi) has been used to study the effect of the absence of lumenal proteases on small intestinal mucosal proteins. The small bowel was divided into eight equal segments. Enzyme activity was increased only in the first three segments in the case of maltase, sucrase, and lactase (all mol wt above 200,000). Alkaline phosphatase (mol wt 145,000), trehalase (mol wt 95,000), and peptidase (mol wt 175,000) activities were unaffected in proximal segments from epi mice. Proximal brush border proteins were identified and measured quantitatively by sodium dodecyl sulfate acrylamide gel electrophoresis. Those enzymes with increased activity were associated with increased amounts of protein in epi mice. Double labeled studies of protein turnover revealed a longer half-life for large brush border proteins (mol wt above 175,000) in epi mice than in normal mice. Enterokinase activity (a marker for duodenal mucosa) was nearly absent from the duodenum of epi mice. Receptors for the intrinsic factor-vitamin B12 complex (markers for ileal mucosal) were present in the ileum equally in normal and in epi mice. Enterokinase activity can be induced in epi mice by feeding its substrate trypsinogen, but not by trypsin or chymotrypsinogen. Epi mice thus retain the ability to synthesize enterokinase. Pancreatic proteases play an important role in the turnover of certain large mucosal proteins and in the induction of enterokinase.
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PMID:Effect of exchange exocrine pancreatic insufficiency on small intestine in the mouse. 20 83

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 activity of the membrane-bound enzymes of the microvillous zone of the entreocytes (maltase, sucrase, trehalase, lactase, cellobiase, alkaline phosphatase and leucylaminopeptidase) was studied in mucosal smears from the proximal jejunum, ileum, caecum and sigmoid flexure in a group of control (C) (8) and germ-free (GF) (7) rabbits. The trypsin and chymotrypsin activity of the contents of the ileum, caecum and sigmoid flexure was studied in 6 C, 5 GF and 5 monocontaminated (MC) rabbits. In summing up it can be stated that the individual membrane-bound enzymes have a different gradient in the various intestinal segments of C and GF rabbits and that they differ reciprocally in character. The maximum statistically significant differences between GF and C rabbits were found in the ileum; in the jejunum they were somewhat smaller and in the caecum smaller still (in this localization the difference was C versus GF). Striking differences in the proportion of the individual disaccharidases were found inthe jejunum and ileum of C rabbits compared with GF rabbits, in which, in both these segments of small intestine the relationship maltase greater than sucrase greater than trehalase greater than lactase was preserved. The proteolytic activity of the intestinal contents likewise had a different gradient character in C, MC and GF rabbits. The maximum activities (especially trypsin) were found in MC animals. The microbial flora is one of the factors regulating the enzymatic activities of the microvillous zone of the enterocytes and it also significantly influences the proteolytic activity of the intestinal contents. This influence is particularly marked in the distal part of the alimentary tube.
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PMID:Digestive enzymes of the mucosa of the small intestine and trypsin and chymotrypsin proteolytic activity of the intestinal contents of germ-free, monocontaminated and conventional rabbits. 35 55

Bacterial extracts were prepared from cultures originating in chronic self-filling intestinal blind loops in rats. Their ability to remove active maltase molecules from isolated brush border membranes was studied in vitro. Twelve strains in 51 tested, belonging to one of three species, Bacteroides fragilis, Clostridium perfringens, and Streptococcus fecalis, possessed maltase-releasing activity. The ability to remove maltase correlated well with the ability to hydrolyze p-nitrophenyl-tert-butyloxycarbonyl-l-alaninate (NBA), an ester substrate rapidly hydrolyzed by elastase, but not with substrated favored by tryhsin and chymotrypsin. Maltase-releasing activity from C. perfringens was strongly inhibited by soybean trypsin inhibitor and to a lesser extent by lima bean trypsin inhibitor. Of four chloromethylketone active-site directed inhibitors tested with specificities for elastase, trypsin, and chymotrypsin, inhibition was maximal with elastase-specific inhibitors. In two species, activity was shown to be heat sensitive, and to be inhibited by concentration of the extract. In one species maltase-releasing activity was shown to be due to an enzyme of molecular weight at least 66,000 with the capacity to remove lactase, sucrase, and alkaline phosphatase, as well as maltase. The results indicate that anaerobic or facultatively anaerobic species, previously identified with the pathology of of the blind loop syndrome, contain proteases which are capable of removing components of the intestinal surface membrane. These proteases appear to have elastase-like substrate specificity and may be involved in the etiology of disaccharidase deficiency in bacterial overgrowth syndromes.
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PMID:Pathogenesis of mucosal injury in the blind loop syndrome. 35

Advances in the study of membrane digestion are described which relate to techniques for the separation of the apical glycocalyx and the study of the distribution of enzymes between the latter and the cell membrane. The regulatory properties of brush border enzymes have been demonstrated. Membrane digestion by pancreatic enzymes adsorbed on the mucosal surface and by enteric enzymes predominates in early development, whereas intraluminal digestion develops during the transition to definitive (adult) nutrition. Substrate and other, non-substrate factors are involved in the regulation of intraluminal and membrane digestion in ontogeny. The importance of lipid components of the diet for the maintenance of proximal-distal gradients of enzyme activity in the small intestine during the transition from milk to adult nutrition is discussed. At this period of development hydrocortisone affects both the synthesis of enzymes and their incorporation into the enterocyte membrane. The inducibility of different enzymes is not identical. The hypothesis has been proposed that stress is one of the factors inducing or repressing the synthesis of brush border enzymes. These effects are mediated through the hypothalamus, adrenals, hypophysis and thyroid. The experimental findings demonstrate that various stressors are responsible for the induction of sucrase, maltases, gamma-amylase, peptidases and alkaline phosphatase, and for the repression of lactase in suckling rats.
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PMID:Membrane digestion and nutrient assimilation in early development. 39 34

The effect of intestinal bacterial over-growth on brush border hydrolases and brush border glycoproteins was studied in nonoperated control rats, control rats with surgically introduced jejunal self-emptying blind loops, and rats with surgically introduced jejunal self-filling blind loops. Data were analyzed from blind loop segments, segments above and below the blind loops, and three corresponding segments in the nonoperated controls. Rats with self-filling blind loops had significantly greater fat excretion than controls and exhibited significantly lower conjugated:free bile salt ratios in all three segments. Maltase, sucrase, and lactase activities were significantly reduced in homogenates and isolated brush borders from the self-filling blind loop, but alkaline phosphatase was not affected. The relative degradation rate of homogenate and brush border glycoproteins was assessed by a double-isotope technique involving the injection of d-[6-(3)H]glucosamine 3 h and d-[U-(14)C]glucosamine 19 h before sacrifice, and recorded as a (3)H:(14)C ratio. The relative degradation rate in both homogenate and brush border fractions was significantly greater in most segments from rats with self-filling blind loops. In the upper and blind loop segments from rats with self-filling blind loops, the (3)H:(14)C ratios were higher in the brush border membrane than in the corresponding homogenates, indicating that the increased rates of degradation primarily involve membrane glycoproteins. Incorporation of d-[6-(3)H]glucosamine by brush border glycoproteins was not reduced in rats with self-filling blind loops, suggesting that glycoprotein synthesis was not affected. Polyacrylamide gel electrophoresis of brush border glycoproteins from the contaminated segments indicated that the large molecular weight glycoproteins, which include many of the surface hydrolases, were degraded most rapidly. Brush border maltase, isolated by immunoprecipitation, had (3)H:(14)C ratios characteristic of the most rapidly degraded glycoproteins. The results indicate that bacteria enhance the destruction of intestinal surface glycoproteins including disaccharidases. Since alkaline phosphatase, a glycoprotein, is not affected, the destruction is selective and presumably involves only the most exposed membrane components.
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PMID:Pathogenesis of mucosal injury in the blind loop syndrome. Brush border enzyme activity and glycoprotein degradation. 41 Aug 30

1. The proteins of the intestinal microvillus membrane have been studied during post-natal development in the rat (days 12--37). 2. In suckling animals (up to age 20 days), the majority of alkaline phosphatase, glucoamylase and lactase activities in the distal half of the intestine were located in the supernatant fraction (100000 X g, 60 min). These enzymes were attached to the membrane from the proximal intestine at all ages. 3. Alkaline phosphatase, maltase and lactase activities in the supernatant fractions chromatographed in Sephadex G-200 in positions similar to the corresponding membrane enzyme. Corresponding activities for lysosomal counter-parts of maltase and lactase present in the supernatant fraction chromatographed differently. Moreover, pH optimum of the soluble enzymes was 9.2 for phosphatase and 5.5--6.0 for glycoamylase and lactase. The soluble lactase and alkaline phosphatase were inhibited minimally by p-chloromercuribenzoate, and sodium fluoride respectively. L-Phenylalanine (20 mM) did inhibit the soluble phosphatase by 90%. Thus, the soluble enzymes are not mainly of the lysosomal origin, but have characteristics of membrane-bound enzymes. 4. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed 18 protein bands which were present in adult membranes. Two other proteins were unique for membranes of distal intestine in suckling rats. The proteins corresponding to known enzyme activity changed as expected with age (e.g. sucrase, maltase increased, lactase decreased). Most of the other proteins were also altered in amount during development. Thus, the changes in the microvillus membrane during development in the rat are not limited to specific enzymes.
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PMID:Development of intestinal brush border membrane proteins in the rat. 41 9

Activities of maltase, sucrase, lactase and acid-beta-galactosidase were studied in jejunum and ileum of term rat fetuses obtained by cesarian section. Female rats were either untreated or injected daily in the last (3rd) week of pregnancy with cortisone acetate (10 or 50 mg/100 g body weight) or L-triiodothyronine (20 or 50 microgram/100 g body weight). Two other control groups were injected with appropriate solvents. Cortisone or T3 treatment to mothers increased sucrase and maltase activity in jejunum and ileum of the offspring. Generally, higher doses of hormone were more effective. Lactase activity was increased by 25% in the jejunum by the higher dose of cortisone. Both doses of cortisone increased ileal lactase. Jejunal acid-beta-galactosidase activity was decreased in fetuses of T3-treated mothers.
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PMID:Effect of cortisone or L-triiodothyronine administration to pregnant rats on the activity of fetal intestinal disaccharidases and lysosomal acid beta-galactosidase. 41 95


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