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:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Developmental profiles describing the expression of lactase, alpha-glucosidase, and alkaline phosphatase activities have been determined quantitatively in mouse jejunal enterocytes during migration over villi and Peyer's patch lymphoid tissue. The predicted maximal lactase and alpha-glucosidase activities expressed by enterocytes migrating over Peyer's patch follicles were about one-quarter and one-half of values found in control villi. Alkaline phosphatase activity was, on the other hand, one third greater in Peyer's patch compared with villus enterocytes. Expression of lactase and alpha-glucosidase activities was initially less in enterocytes migrating along interfollicular compared with control villi. Subsequent increase in hydrolase activities occurred during the later stages of enterocyte migration over interfollicular villi. Lactase activity in athymic mice Peyer's patch enterocytes was identical to that recorded for control mice. The corresponding value for villus lactase was, however, only half that found in control tissue. Factors produced locally in lymphoid follicles are probably responsible for selective effects on enterocyte differentiation.
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PMID:Selective expression of brush border hydrolases by mouse Peyer's patch and jejunal villus enterocytes. 393 May 23

1. A method for the preparation of brush border from rabbit kidneys is described. Contamination by other organelles was checked by electron microscopy and by the assay of marker enzymes and was low. 2. Seven enzymes, all hydrolases, were substantially enriched in the brush-border preparation and are considered to be primarily located in this structure. They are: alkaline phosphatase, maltase, trehalase, aminopeptidase A, aminopeptidase M, gamma-glutamyl transpeptidase and a neutral peptidase assayed by its ability to hydrolyse [(125)I]iodoinsulin B chain. 3. Adenosine triphosphatases were also present in the preparation, but showed lower enrichments. 4. Alkaline phosphatase was the most active phosphatase present in the preparation. The weak hydrolysis of AMP may well have been due to this enzyme rather than a specific 5'-nucleotidase. 5. The two disaccharidases in brush border were distinguished by the relative heat-stability of trehalase compared with that of maltase. 6. The individuality of the four peptidases was established by several means. The neutral peptidase and aminopeptidase M, both of which can attack insulin B chain, differed not only in response to inhibitors and activators but also in the inhibitory effect of a guinea-pig antiserum raised to rabbit aminopeptidase M. This antiserum inhibited both the purified and the brush-border activities of aminopeptidase M. The neutral peptidase and gamma-glutamyl transpeptidase were unaffected but aminopeptidase A was weakly inhibited. The characteristic responses to Ca(2+) and serine with borate served to distinguish aminopeptidase A and gamma-glutamyl transpeptidase from other peptidases. 7. No dipeptidases, tripeptidases or carboxypeptidases were identified as brush-border enzymes. 8. Incubation of brush border with papain released almost all the aminopeptidase M activity but only about half the activities of maltase, gamma-glutamyl transpeptidase and aminopeptidase A. No release of alkaline phosphatase, trehalase or the neutral peptidase was observed.
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PMID:Studies on the enzymology of purified preparations of brush border from rabbit kidney. 414 72

1. Brush borders were isolated from rabbit kidney-cortex homogenates by rate-zonal centrifugation through a sucrose density gradient in a B-XIV zonal rotor, followed by differential centrifugation. 2. The method of preparation gave brush borders of high purity with a reasonable yield. The morphological appearance supported the evidence from enzymic and chemical investigations, that the brush borders were only slightly contaminated with endoplasmic reticulum, mitochondria, lysosomes and nuclei. 3. The molar ratio of cholesterol to phospholipid lay within the range found in other plasma membranes, but the carbohydrate content was double that found in liver plasma membranes. 4. Alkaline phosphatase, maltase, trehalase and aminopeptidase were major enzymic constituents of the brush borders, and had an approximately equal yield and enrichment, but none of these enzymes fulfilled the criteria for marker enzymes. 5. Mg(2+)-dependent and Na(+),K(+)-dependent adenosine triphosphatases, although found in brush borders, had low yields and low enrichments.
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PMID:Isolation and characterization of rabbit kidney brush borders. 426 1

Human jejunal biopsy slices were maintained in culture for up to 48 hours. At 24 hours there was good morphological preservation but by 48 hours there was ultrastructural evidence of damage to the enterocytes. During culture the tissue had lost a certain amount of protein. At the same time the levels of three brush border enzymes (alkaline phosphatase, alpha-glucosidase, and leucyl-beta-naphthylamidase) and one lysosomal enzyme (N-acetyl-beta-glucosaminidase) showed a progressive decrease. Alkaline phosphatase, alpha-glucosidase, and N-acetyl-beta-glucosaminidase accumulated in the medium throughout the experimental period to give a medium:tissue distribution ratio of between 2 and 9. Leucyl-beta-naphthylamidase had a medium:tissue ratio of 140 after 48 hours of culture suggesting a selective secretion of this enzyme by the tissue.
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PMID:Enzyme changes in human small bowel mucosa during culture in vitro. 443 22

After twenty weeks of continuous dosing with Trichostrongylus colubriformis larvae substantial, but declining, numbers of worms had persisted in most of the lambs examined, although there were wide inter-individual variations. Mucosal lesions were found in the proximal small intestines of all the infected animals, their severity being directly related to worm burden. Representative brush border enzyme activities analysed in intestinal mucosal extracts from the same lambs showed differing responses. Alkaline phosphatase and glycyl-L-leucine dipeptidase were significantly depleted, whereas maltase activity was only marginally reduced, and leucine aminopeptidase activity was normal. Mucosal acetylcholinesterase activity was significantly elevated in the parasitised animals and, interestingly in view of the postulated role of this enzyme in nematode pathogenicity, the level of activity was directly correlated with individual worm burdens. Intestinal trypsin and chymotrypsin activities were unaffected and the level of superoxide dismutase, an enzyme associated with the inflammatory response, was normal. There were also no consistent changes in the mucosal activities of several enzymes including lactic dehydrogenase, creatine phosphokinase, aldolase, and glutamic oxaloacetate transaminase, whose leakage from damaged or necrotic tissues has been well defined in terms of the concomitant increase in their activity in the circulation. Lambs treated orally with fenbendazole five and/or ten weeks before slaughter either in the presence or absence of continued larval intake, had negligible worm burdens, and showed little evidence of intestinal damage at post mortem. Brush border enzyme levels, with the exception of alkaline phosphatase and, in two cases dipeptidase, were normal in these animals. The activity of alkaline phosphatase was approximately double that in the continuously infected, untreated lambs, but remained markedly lower than in the uninfected controls. The activities of the other enzymes studied, including acetylcholinesterase, were within the control range. In summary, in chronic trichostrongylosis even relatively low nematode burdens were associated with marked pathological and biochemical damage in the intestine with both lesion severity and mucosal acetylcholinesterase activity being directly related to worm numbers. Although morphological integrity was completely restored after anthelmintic treatment, the persistent low activity of brush border alkaline phosphatase coupled with the enzymological findings in untreated, infected animals suggests that recovery of the full functional capability of the intestinal mucosa may take longer.
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PMID:Intestinal enzyme activity in lambs chronically infected with Trichostrongylus colubriformis: effect of anthelmintic treatment. 634 11

We explored whether glucocorticoid administration, a known stimulus of renal gluconeogenesis (GNG), could decrease avid inorganic phosphate (Pi) reabsorption in rats stabilized on low-phosphorus diet (LPD). Rats adapted to LPD were injected with the glucocorticoid (GCD) triamcinolone acetonide (1.25 or 2.5 mg.100 g body wt-1.day-1 ip) for 2 days; they showed a profound increase in urinary excretion of Pi during the injection period. In clearance studies GCD increased the clearance and fractional excretion of Pi but did not change the filtered load of Pi. Initial "uphill" Na+-gradient (Nao+ greater than Nai+)-dependent uptake of 32Pi by luminal brush-border membrane (BBM) vesicles prepared from renal cortex of rats treated with GCD was markedly (greater than 40%) decreased compared with control rats; Na+-gradient-dependent uptake of D-[3H]glucose was not diminished. At the "equilibrium" time interval, measured at 120 min, BBM vesicles from control and GCD-treated rats did not differ in the uptake of 32Pi or D-[3H]glucose. With kinetic analysis, BBM from GCD-treated rats showed a marked decrease (-40%) in the maximum velocity (Vmax) of initial Na+-dependent 32Pi uptake, but the apparent affinity of the BBM transport system for Pi (apparent Km = 0.078 mM Pi) was not different from that of controls. Alkaline phosphatase specific activity was much lower (-40%) in BBM from GCD-treated rats compared with controls, but the activities of three other BBM enzymes (maltase, leucine aminopeptidase, and gamma-glutamyl transferase) were not different. The addition of triamcinolone to BBM in vitro had no effect on either Na+-dependent uptake of 32Pi or alkaline phosphatase activity. The rate of GNG from alpha-ketoglutarate was significantly increased in cortical slices from GCD-treated rats adapted to LPD. Also, the NAD+-to-NADH ratio was higher in the renal cortex of GCD-treated rats, although the total content of NAD [NAD+ + NADH] was not different from controls. Renal excretory, BBM, and metabolic changes elicited controls. Renal excretory, BBM, and metabolic changes elicited by GCD treatment were similar in intact and thyroparathyroidectomized rats. Phosphaturia elicited in rats fed LPD by GCD administration in vivo appears to be at least in part due to a decreased capacity of luminal BBM of proximal tubules for decreased capacity of luminal BBM of proximal tubules for Na+-dependent uptake of Pi. Although the causal relationship between observed parameters is not established, our results are compatible with the interpretation that an increase in the rate of renal GNG, perhaps via action of NAD+ on BBM (J. Clin. Invest. 67: 1347-1360, 1981), decreases luminal uptake and reabsorption of Pi in proximal tubules.
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PMID:Mechanism of glucocorticoid effect on renal transport of phosphate. 675 2

Nine lysosomal enzymes and alkaline phosphatase have been assayed in human pancreatic juice from controls and patients with chronic calcifying pancreatitis. Specific activities were evaluated by a nonparametric test (Wilcoxon) with a probability of 2 P less than or equal to 0.5. The values of acid phosphatase, alpha-glucosidase, beta-glucosidase and alpha-galactosidase are significantly higher in pathological juices; the values of alpha-mannosidase and beta-glucuronidase are also increased in the same patients but at the limit of significance. Alkaline phosphatase, beta-hexosaminidase and alpha-fucosidase follows the same trend but the values are not statistically significant between the two groups of patients. Studies on skin cultures of four patients with chronic calcifying pancreatitis demonstrate that the increased specific activities of lysosomal enzymes in the pathological juices do not correspond to a leakage of these enzymes into the extracellular space as described for cystic fibrosis.
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PMID:Alkaline phosphatase and acid lysosomal hydrolases in pancreatic juice and fibroblast cell cultures of patients with chronic calcifying pancreatitis. 680 85

The development of intestinal brush border hydrolytic activities has been studied during thyroxine-induced metamorphosis of Rana catesbeiana. Alkaline phosphatase activity peaks at 3 and 10 days after the beginning of the thyroxine treatment. The cytochemical observations concerning alkaline phosphatase activity are in agreement with the biochemical data. At the ultrastructural level, alkaline phosphatase activity is particularly evident on the microvilli membranes of the enterocytes in the primary epithelium after 3 days and in the secondary epithelium after 10 days. gamma-Glutamyltranspeptidase exhibits an increase of activity between 7 and 10 days. On the other hand, glucoamylase, maltase, trehalase and leucylnapthylamidase activities decrease during thyroxine treatment, these enzymatic activities being lower than that normally observed after natural metamorphosis. The present study indicates that even though thyroxine is able to induce the morphological differentiation of the intestinal epithelium this hormone is unable to complete the enzymatic load of the new mucosa.
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PMID:Amphibian intestinal brush border enzymes during thyroxine-induced metamorphosis. 697 Jan 91

Left kidneys of rats were made ischemic for 25 minutes and proximal tubule brush border alterations studied in the S1 and S2 segments. Scanning electron microscopy revealed that brush border microvilli became unstable, fused with one another, and were interiorized into proximal tubule cytoplasm soon after reflow of blood following ischemia. Rapid regeneration followed; scanning electron microscopy showed that regeneration occurred in a fashion whereby clusters of microvilli in flower-like configurations were extruded from the cell interior toward the surface. Such unique patterns of microvillus formation have not been reported before. Activity of the brush border enzymes, alkaline phosphatase and maltase, were not significantly depressed throughout the cycle of brush border loss and regeneration. Likewise, there were no alterations in the activity of beta-glucuronidase, a lysosomal enzyme. Alkaline phosphatase cytochemistry showed that microvillus membranes that were interiorized into the cell cytoplasm retained enzyme activity on their surfaces during the early period of brush border loss as well as during regeneration. These results strongly suggest that in reversibly injured proximal tubule cells regeneration of the brush border occurs primarily by a process of recycling of damaged, previously incorporated membrane. The nature of the initial membrane damage and the mechanism of recycling remain unknown.
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PMID:Mechanism of proximal tubule brush border loss and regeneration following mild renal ischemia. 730 Feb 48

This study has identified a naturally occurring, specific deficiency of a brush border aminopeptidase N (ApN) in the small intestines of five clinically healthy dogs. ApN activity in mucosal homogenates of dog small intestine was reduced significantly in deficient animals (13.4 (1.1) nmol min-1 mg-1 protein, n = 5, P < 0.002) compared to healthy control dogs (95.1 (6.7), n = 22). Alkaline phosphatase, gamma-glutamyl transferase, zinc-resistant alpha-glucosidase, maltase, sucrase and lactase in the ApN deficient dogs exhibited comparable activities to those in the control dogs. Microvillar membranes were analysed by one- and two-dimensional electrophoresis. ApN was represented by a single 145kDa band in all control dogs, identified by immunoblotting and immunoprecipitation. Protein maps from deficient dogs were normal apart from the virtual absence of an ApN spot and there were no apparent abnormalities in the glycosylation of microvillar proteins. The findings suggest that intestinal ApN deficiency in these dogs is a primary lesion involving diminished expression of an otherwise normal enzyme protein.
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PMID:An aminopeptidase N deficiency in dog small intestine. 942 46


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