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)

Protein sulfation in small intestinal epithelial cells was studied by labelling of organ cultured mucosal explants with [35S]-sulfate. Six bands in SDS-PAGE became selectively labelled; four, of 250, 200, 166 and 130 kd, were membrane-bound and two, of 75 and 60 kd, were soluble. The sulfated membrane-bound components were all enriched in the microvillar fraction but either absent or barely detectable in intracellular or basolateral membranes. Immunopurification of sucrase-isomaltase, maltase-glucoamylase, aminopeptidase N and aminopeptidase A showed that these microvillar enzymes become sulfated. Most if not all the sulfate was bound to tyrosine residues rather than to the carbohydrate of the microvillar enzymes, showing that this type of modification can occur on plasma membrane proteins as well as on secretory proteins.
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PMID:Tyrosine sulfation, a post-translational modification of microvillar enzymes in the small intestinal enterocyte. 312 1

The function of membrane cholesterol (chol) in the regulation of membrane-bound hydrolases and transport proteins has been investigated in chol-enriched membranes of guinea pig intestinal brush borders. Chol-enrichment is accomplished by non-invasive means i.e., dietary manipulation by high-chol diet feeding. Activities of sucrase, lactase and maltase enzyme systems, Na+-dependent and -independent glucose transport and calcium uptake are found to be greatly inhibited by chol both at 22 degrees C and 37 degrees C. Glucose and calcium uptake in native membranes are found to be temperature sensitive processes and produce nonlinear Arrhenius plots with a transition temperature around 22 degrees C. The discontinuity in the Arrhenius expression is lost in chol enriched membranes which is interpreted as the increase in microviscosity imparted by chol in the bulk lipid phase environment where these proteins operate.
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PMID:Effect of cholesterol and temperature perturbations on membrane hydrolases and transport of calcium and glucose in guinea pig brush border membrane vesicles. 317 55

Soluble and membrane-bound forms of neutral alpha-glucosidase, which are immunologically similar to the corresponding forms of kidney enzymes, were found in urine of healthy persons and of patients with kidney impairments. Membrane-bound enzyme was only slightly active in urine of healthy persons and constituted 3-10% of total urine activity although the ratio of membrane-bound enzyme was simultaneously elevated under pathological conditions. The increased rate of soluble enzyme secretion was responsible for distinct activation of neutral alpha-glucosidase in urine of the patients with kidney impairments.
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PMID:[Soluble and membrane-bound forms of neutral alpha-glucosidase in human urine in normal conditions and in kidney diseases]. 328 88

A newly recognized inherited metabolic disease in the Lapland dog is described. The metabolic defect is a deficiency of acid-alpha-glucosidase, a lysosomal hydrolase. The clinical picture is dominated by vomiting related to megaoesophagus, and progressive muscle weakness leading to exhaustion and death before two years of age. Cardiac abnormalities are observed. The main histopathologic lesion consists of glycogen accumulation, notably in membrane-bound vacuoles (glycogenosomes), involving all kinds of muscular tissue in particular. Recessive inheritance of the disease was demonstrated by complementation analysis. The enzyme protein is present in affected tissues, although in an inactive form. Based on the gene dosage phenomenon, an attempt was made to identify carrier dogs by means of a biochemical assay. Glycogen storage disease type II in the Lapland dog appears to be a homologous model for the infantile manifestation of glycogen storage disease type II (Pompe's disease) in man.
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PMID:Glycogen storage disease type II in the Lapland dog. 390 97

Highly purified microvillus membrane vesicles isolated from rat small intestine were enriched in sucrase, maltase, and aminopeptidase activities. Approximately 90-95% of each enzyme was released from the membrane fraction by treatment with detergent (Triton X-100) and sonication. Using untreated and solubilized preparations, the effect of lectin binding on the activity of each of the three enzymes was measured. It was observed that wheat germ agglutinin (WGA) and phytohemagglutinin (PHA) dramatically enhanced the activity of membrane-bound maltase but had much less effect on the detergent solubilized enzyme. Under the same conditions aminopeptidase activity was inhibited by WGA and PHA while sucrase activity was not affected. These alterations in enzyme activity occurred at lectin concentrations that also precipitated each solubilized enzyme from solution. Inhibitory sugars prevented the alterations in enzyme activity suggesting that the effect is due to the binding of lectin to specific carbohydrate structures. Enhancement of membrane-bound maltase activity by WGA and PHA was shown to be temperature dependent indicating that the lipid environment of the microvillus membrane may play a role in mediating the lectin effect. A kinetic analysis of the changes in maltase activity induced by these two lectins was due solely to an increase in Vmax. Two other lectins used in this study (concanavalin A and Ricinus communis agglutinin) did not readily precipitate the enzymes in question or alter their activity. These results show that binding of lectins to brush border membranes can induce variable changes in the activity of several membrane associated hydrolases, and suggest that similar changes may occur in vivo in the presence of dietary lectin.
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PMID:Effect of lectins on the activity of brush border membrane-bound enzymes of rat small intestine. 390 78

Oral (p.o.) administration of a single dose of kalmegh leaf extract (KE; 0.5 g/kg and 1.0 g/kg) or andrographolide (A; 5 mg/kg and 10 mg/kg) to adult male albino rats (100-120 g) produced a dose-related and time-dependent characteristic activation of brush-border membrane-bound hydrolases, viz. lactase, maltase and sucrase in three regions of small intestine (viz. duodenum, jejunum and ileum). The maximum stimulation of these disaccharidases was obtained at 6 hr of either KE or A administration. Further, it was also noted that the extent of activation of the disaccharidases with KE or A, both at higher and lower doses, followed the order: (a) Maltase greater than sucrase greater than lactase in duodenum and (b) Maltase greater than lactase greater than sucrase in jejunum and ileum. Long term administration (for 7, 15 and 30 consecutive days) of either KE (500 p.o.) or A (5 mg/kg/day; p.o.) stimulated lactase, maltase and sucrase in all parts of the small intestine. Maximum stimulation of lactase and maltase was noted after 30 consecutive days of treatment while sucrase exhibited maximum activation after 15 consecutive of treatment with either KE or A. These results suggest that both KE and A accelerate intestinal digestion and absorption of carbohydrate by activating these intestinal disaccharidases.
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PMID:Andrographolide and kalmegh (Andrographis paniculata) extract: effect on intestinal brush-border membrane-bound hydrolases. 393 7

Rectal biopsy specimens from control subjects and from patients with Crohn's colitis, non-rectal Crohn's disease, and acute ulcerative colitis were homogenized in isotonic sucrose and subjected to analytical subcellular fractionation by sucrose density gradient centrifugation. The gradient fractions and tissue homogenates were assayed for marker enzymes for the principal organelles: 5'nucleotidase (plasma membrane), malate dehydrogenase (mitochondria), catalase (peroxisomes), lactate dehydrogenase (cytosol), N-acetyl-beta-glucosaminidase (lysosomes), and neutral-alpha-glucosidase (endoplasmic reticulum). In normal tissue there was a distinct plasma membrane peak at density 1.12 g/ml. In tissue from patients with Crohn's disease the activity was increased approximately twofold even when the rectum showed no evidence of histological involvement. A second plasma membrane component was noted in Crohn's disease at density 1.19 g/ml. The total activity of the mitochondrial enzyme was similar in the various patient groups, but there was evidence of mitochondrial damage. There were no significant alterations in activity and density gradient distributions of catalase or of neutral alpha-glucosidase in the various patient groups, although less membrane-bound lactate dehydrogenase was noted in the patients with inflammatory bowel disease. There was a reduction of both cytosolic and particulate N-acetyl-beta-glucosaminidase in ulcerative colitis and a selective reduction in particulate activity in non-rectal Crohn's disease, demonstrating lysosomal alterations in these disorders. These results indicate selective and specific alterations in the principal subcellular organelles, especially the plasma membrane, lysosomes, and mitochondria, in the inflammatory bowel disease.
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PMID:Subcellular fractionation of rectal biopsy homogenates from patients with inflammatory bowel disease. 399 79

The 100000g supernatants from 13-day-old suckling-rat intestinal homogenates contained 43.5% of the total intestinal maltase activity, compared with 7.1% in weaned adult rats aged 40 days. The soluble maltase activity was separated on Sepharose 4B into two quantitatively equal fractions at pH6.0, one containing a maltase with a neutral pH optimum and the other a maltase with an acid pH optimum. The neutral maltase was shown to be a maltase-glucoamylase identical with membrane-bound maltase-glucoamylase in molecular weight, heat-sensitivity, substrate specificity, K(m) for maltose and K(i) for Tris. The soluble enzyme was induced by cortisol, but the ratio of the soluble to bound enzyme fell during induction. Solubility of the neutral maltase was not accounted for by the action of endogenous proteinases under the preparative conditions used. It is postulated that the soluble neutral maltase is a membrane-dissociated form of the bound enzyme and that the relationship between these two forms is modulated by cortisol. The acid maltase generally resembled acid maltase of liver, muscle and kidney. It was shown to be a maltase-glucoamylase with optimal activity at pH3.0, and molecular weight of 136000 by density-gradient centrifugation. At pH3.0 its K(m) for maltose was 1.5mm. It was inhibited by turanose (K(i)=7.5mm) and Tris (K(i)=5.5mm) but not by p-chloromercuribenzoate or EDTA. Some 55% of its activity was destroyed by heating at 50 degrees C for 10min. The acid maltase closely resembled beta-glucuronidase and acid beta-galactosidase in its distribution in the intestine, response to tissue homogenization in various media, and decrease in activity with cortisol treatment and weaning, indicating that it was a typical lysosomal enzyme concentrated in the ileum.
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PMID:Soluble neutral and acid maltases in the suckling-rat intestine. The effect of cortisol and development. 421 59

Two groups of mutants altered in lytic enzyme activities have been isolated from Bacillus licheniformis 6346 MH-1 by screening clones for halo production in agar plates containing cell wall conjugated with Procion brilliant red. In the first group which produced halos during colony formation, two were shown to contain three- and eightfold more muramyl-l-alanine amidase than the parent. These strains liberated amidase and intracellular alpha-glucosidase into the culture medium during exponential growth in liquid medium. Isolated walls had a normal qualitative composition and in autolysing liberated N-terminal amino acids and reducing groups. Wall preparations from the second group of mutants which did not produce halos lysed very poorly at pH 9.5, the optimal pH for amidase activity, and poorly at pH 5.5 even though they had similar endo-N-acetylglucosaminidase activities to the parent. Two of these strains that were also deficient in phosphoglucomutase had only 3 to 5% of the membrane-bound amidase activity compared with that in the parent. Cell walls of the phosphoglucomutase-deficient mutants treated with sodium dodecyl sulfate to inactivate endogenous lytic enzymes were dissolved at 10% of the rate of those from the parent by added amidase, but their sensitivities to lysozyme were similar. Those from one mutant had 10 to 20% of the amidase-binding capacity of parent walls, whereas its isolated mucopeptide was essentially inactive in this respect. The failure of these phosphoglucomutase-deficient mutants to autolyse is likely to be due to the combined effects of both low amidase activity and resistant walls. As a result, daughter cells are unable to separate and long chains are formed during exponential growth.
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PMID:Characterization of Bacillus licheniformis 6346 mutants which have altered lytic enzyme activities. 482 3

Bloodstream forms of Trypanosoma brucei have been screened for the presence of enzymes that could serve as markers for the plasma membrane, flagellar pocket, lysosomes, endoplasmic reticulum and Golgi apparatus in order to study the subcellular organization of the digestive system of the parasite. Acetylesterase, acid DNase, acid phosphatase, acid phosphodiesterase, acid proteinase, acid RNase, alanine aminotransferase, galactosyl transferase, alpha-glucosidase, inosine diphosphatase and alpha-mannosidase were partially characterized and their assays optimized for pH-dependent activity, linearity of reaction with respect to incubation time and enzyme concentration, and the effect of inhibitors and activators. The association of these enzymes with particulate material and the presence of structural latency were investigated. Acid proteinase and alpha-mannosidase are particle-bound and latent in cytoplasmic extracts; they can be activated and solubilized in part by Triton X-100. Similar results were obtained for acid phosphatase, acid phosphodiesterase and inosine diphosphatase. Neutral alpha-glucosidase, though partly sedimentable, does not show latency and is readily solubilized by the detergent. Galactosyl transferase is firmly membrane-bound even in the presence of 0.1% Triton X-100. Cell fractionation by differential centrifugation and density equilibration on sucrose gradients revealed that both alpha-mannosidase and acid proteinase are associated with organelles that band at a density of about 1.20 g/cm3. Inosine diphosphatase, galactosyl transferase, acid phosphatase and acid phosphodiesterase sediment predominantly as microsomal constituents equilibrating at densities between 1.13 and 1.15 g/cm3. In addition, inosine diphosphatase and galactosyl transferase exhibit considerable activity at higher densities (1.18-1.25 g/cm3). Neutral alpha-glucosidase is mainly recovered in the nuclear and microsomal fraction; its particulate part equilibrates as a single band at rho = 1.22 g/cm3. Acetylesterase and acid DNase are largely soluble, whereas acid RNase does not produce distinct sedimentation and banding profiles. In intact cells, neutral alpha-glucosidase and acid phosphatase appear to be highly accessible to their substrates. It is tentatively concluded that (a) acid proteinase and alpha-mannosidase are lysosomal enzymes, (b) acid phosphatase and acid phosphodiesterase are associated with the flagellar pocket and part of the former enzyme probably with the endoplasmic reticulum, (c) galactosyl transferase is a constituent of the Golgi apparatus, and (d) alpha-glucosidase may serve as a marker for the plasma membrane. Inosine diphosphatase may also be derived from the latter structure.
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PMID:Subcellular fractionation of Trypanosoma brucei bloodstream forms with special reference to hydrolases. 624 76


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