Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzyme-gold approach was applied for ultrastructural localization of glucoside residues in animal and plant tissues. A beta-glucosidase-gold complex was prepared and used on thin tissue sections to reveal the corresponding substrate molecules by electron microscopy. Conditions for preparation of the complex, as well as for its application, were determined. Once applied on thin tissue sections, the glucosidase-gold complex yielded labeling over the rough endoplasmic reticulum, mainly on the ribosomal side of the membranes, and over the dense chromatin in the nucleus. Mitochondria, Golgi apparatus, and secretory granules in liver and pancreatic cells were free of gold particles. In plant cells, the labeling pattern was similar. In addition, the stroma regions of chloroplasts were densely labeled. In the extracellular space, labeling was found over the basal laminae of cells in animal tissues and over the fibrillar wall material bordering the intercellular space in plant tissues. Fungal cell cytoplasm was also labeled, as well as the membrane delineating mycoplasma-like organisms. Control conditions confirmed these labelings, demonstrating the possibility of revealing glucoside residues on tissue sections with high resolution and specificity.
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PMID:Ultrastructural localization of glucoside residues on tissue sections by applying the enzyme-gold approach. 311 63

Hydrolysis of p-nitrophenyl-beta-D-glucoside by cytosolic beta-glucosidase proceeds with retention of the anomeric configuration. Whereas inactivation of the enzyme by the glucosidase inhibitor conduritol B epoxide (CBE) was extremely slow (ki(max)/Ki 0.57 M-1 min-1) it reacted 130 times more rapidly with 6-bromo-6-deoxy-CBE (Br-CBE). The beta-glucosidase could be labeled with [3H]Br-CBE; incorporation of 1 mol inhibitor/mol enzyme resulted in complete loss of activity. Most of the bound inhibitor was released after denaturation and treatment with ammonia as (1,3,4/2,5,6)-6-bromocyclohexanepentol, thus demonstrating the formation of an ester bond with an active site carboxylate by trans-diaxial opening of the epoxide ring. It was concluded from the Ki values for the epoxide inhibitors and for coduritol B with the cytosolic enzyme and corresponding data for the lysosomal beta-glucosidase that the unusually low reactivity with CBE and Br-CBE is probably due to the inability of the cytosolic enzyme to effectively donate a proton to the epoxide oxygen. An extremely rapid inactivation of the cytosolic beta-glucosidase was caused by bromoconduritol F ((1,2,4/3)-1-bromo-2,3,4-trihydroxycyclohex-5-ene) with ki(max)/Ki 10(5) M-1 min-1. In contrast with the Br-CBE-inhibited enzyme the beta-glucosidase inhibited by bromoconduritol F was subject to spontaneous reactivation with t1/2 approximately 20 min.
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PMID:Active site directed inhibition of a cytosolic beta-glucosidase from calf liver by bromoconduritol B epoxide and bromoconduritol F. 312 52

In primary astrocyte cultures beta-glucosidase (EC 3.2.1.21) and beta-galactosidase (EC 3.2.1.23) showed pH optima and Km values identical to rat brain enzymes, using methylumbelliferyl glycosides and labeled gluco- and galactocerebrosides as substrates. The activities of both glycosidases increased in culture up to 3-4 weeks. In rat brain only galactosidase increased; glucosidase activity declined between 12-20 days after birth. The specific activities were two- to sixfold higher in astrocyte cultures than in rat brain. These activities were not due to uptake of enzymes from the growth medium. Secretion of beta-galactosidase, but not beta-glucosidase nor acid phosphatase could be demonstrated. These results support the suggestion of a degradative function for astrocytes in the brain.
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PMID:beta-Glucosidase and beta-galactosidase in primary cultures of rat astrocytes: comparison to the brain enzymes. 391 92

Activity of lysosome enzymes (acidic phosphatase, beta-glucosidase, DNAase, RNAase and cathepsin D) is determined for its variation in different organs of rainbow trout during complete fasting. It is shown that the activity of most enzymes of concern almost in all organs except skeletal muscles is on the higher level in trouts fasted for 30 days than in the control ones. With an increase of the fasting term to 60 days the acid phosphatase, DNAase, RNAase activity decreases while the glucosidase and cathepsin D activity in some organs increases. Variations detected in the enzyme profile of the trout lysosomes under fasting are of adaptive character.
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PMID:[Changes in the activity of trout lysosomal enzymes during fasting]. 392 43

Unusual kinetic behaviour was observed in assaying spectrophotometrically for exo-glucanase activity in a beta-glucosidase isolated from A. faecalis using p-nitrophenyl beta-cellobioside as substrate. At high substrate concentrations no phenol was released whereas at low concentrations a rapid release of phenol was detected and this increased in rate with extent of hydrolysis. These results are consistent with a model involving tight binding of the substrate to the enzyme and an initial exo-glucosidase-catalysed hydrolysis to produce glucose and p-nitrophenyl glucoside. Subsequent hydrolysis of the nitrophenyl glucoside results in phenol release, but only after sufficient concentrations have accumulated to compete with the cellobioside. This theory was confirmed by product analysis and by measuring the affinity of the substrate for the enzyme by its inhibition of p-nitrophenyl glucoside hydrolysis. Observation of such kinetic behaviour allows distinction between beta-glucosidase and exo-glucosidase activities.
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PMID:A simple kinetic test to distinguish exo-glucosidase and beta-glucosidase activities. 393 98

1. Cell-free culture filtrates of the fungus Fusarium solani were examined for homogeneity with respect to beta-d-glucosidase and C(x) activities. 2. o-Nitrophenyl beta-d-glucoside and cellobiose were both used as substrates for beta-d-glucosidase activity. 3. No evidence for the non-identity of nitrophenyl beta-d-glucosidase and cellobiase activities could be found, either by heat treatment, gel filtration on Sephadex G-100 or by isoelectric focusing. 4. The beta-d-glucosidase component was also a feeble exo-beta-glucanase: it had a molecular weight of approx. 400000. 5. The fall in viscosity of a solution of CM-cellulose, the formation of reducing sugars in a solution of CM-cellulose and the solubilization of phosphoric acid-swollen cellulose (Walseth cellulose), were all used for the measurement of C(x) activity. 6. The ratio of the two types of CM-cellulase activity was not changed after gel filtration on Sephadex G-100 or after chromatography on DEAE-Sephadex. 7. Three peaks of C(x) activity were obtained after electrofocusing, but all three possessed the same ratio of the two types of CM-cellulase activity as well as the same CM-cellulase/Walseth activity ratio, as the unfractionated enzyme; all three isoenzymes (isoelectric points, 4.75, 4.80-4.85 and 5.15) acted in synergism with a mixture of the C(1) and the beta-d-glucosidase components to the same extent in the solubilization of cotton fibre. 8. The molecular weight of the C(x) component was approx. 37000.
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PMID:The cellulase of Fusarium solani. Purification and specificity of the -(1-4)-glucanase and the -D-glucosidase components. 511 66

The enzymic hydrolysis of glycosyl fluorides is conveniently followed by using a pH-stat. Reactions involving glucosyl or galactosyl fluorides can also be followed by using glucose oxidase or galactose oxidase respectively. The pH-stat allows the rapid assay of intestinal alpha-glucosidase in crude homogenates. Use of glycosyl fluorides as substrates for glycosidases facilitates the polarimetric or g.l.c. determination of the anomeric nature of the initial product of hydrolysis. Hydrolysis by fungal amyloglucosidase proceeds with inversion of configuration whereas that by yeast and rat intestinal alpha-glucosidase, coffee-bean alpha-galactosidase and almond emulsin beta-glucosidase proceeds with retention of configuration. beta-d-Glucopyranosyl azide was not a detectable substrate for almond emulsin beta-d-glucosidase.
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PMID:The hydrolysis of glycosyl fluorides by glycosidases. Determination of the anomeric configuration of the products of glycosidase action. 512 11

Mycelial enzyme extracts of Schizophyllum commune were prepared during vegetative growth matings leading to common-A and common-B heterokaryons and the dikaryon, and were examined for hydrolytic activity against an alkaliinsoluble cell-wall glucan (R-glucan) isolated from this mushroom. In extracts from several individual homokaryotic mycelia the R-glucanase activity was low and did not increase when the cultures exhausted glucose in the medium. In common-A matings, a 30-fold increase in specific activity of intracellular R-glucanase was found even in the presence of glucose in the broth. An increase of this magnitude was not observed in the common-B mating nor in the fully compatible cross leading to the dikaryon. Extracts of the dikaryon did show elevated R-glucanase activity after exogenous glucose disappearance and subsequent fruiting. In none of these situations was an enzyme activity detected towards an alkali-soluble cell-wall glucan (S-glucan) prepared from S. commune. Changes in R-glucanase were not parallelled by identical changes in laminarinase, pustulanase, cellobiase, and p-nitrophenyl-beta-d-glucosidase, but comparable increases in specific activities were found for hydrolysis of glycogen and maltose. After interaction of the various mycelia in mating combinations, the S-glucan/R-glucan ratio of the cell wall of the dikaryon was found to be similar to that of the homokaryons, but increased in the common-B interaction and was elevated almost threefold in the common-A heterokaryon.
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PMID:Role of a cell-wall glucan-degrading enzyme in mating of Schizophyllum commune. 605 8

The degradation of cyanogenic glycosides was studied in spontaneously fermenting cassava root pulp and in fresh pulp samples pretreated to prevent either endogenous beta-glycosidase activity, fermentation, or both. The rate of disappearance of the glycosides, as measured by hydrocyanic acid (HCN) production in situ, in membrane-sterilised media or in samples containing 1% sodium iodoacetate, was comparable with the untreated control in which 85% of the substrate was broken down within 72 h. Pretreatment of the fresh pulp with the beta-glucosidase inhibitor 1,5-gluconolactone (1%) markedly reduced the rate of disappearance of the cyanogens while inclusion of glucose in this test medium at the 3% level appeared to induce some hydrolysis. Loss of bound (glycosidic) cyanide in sterilised medium containing the glucosidase inhibitor was negligible. The results suggest that the contribution of the fermentation process in cyanide detoxification of pulped cassava roots is minimal.
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PMID:Differential effects on the cyanogenic glycoside content of fermenting cassava root pulp by beta-glucosidase and microbial activities. 640 10

In order to study the influence of biliary secretions on the in situ kinetic data of brush border disaccharidases in relation to small intestinal villus-crypt architecture, an anastomosis was constructed between the common bile duct, which had been divided before its entrance into the pancreatic head, and the ileum in adult female Wistar rats. Simple attachment of the terminal ileum to the liver hilum was performed in the controls. Six weeks after the operation, tissue sections were prepared from duodenum and ileum of biliary-diverted and control animals (n = 5 in each group) and examined by section biochemistry and morphometry. In both groups the apparent Vmax values of neutral alpha-glucosidase and lactase/beta-glucosidase, measured at the villus base and at its apex, and the villus height were decreased from the duodenum towards the distal ileum. After biliary diversion to the ileum, an increase in villus height ensued in this segment, and the increasing gradient of glucosidase activity towards the villus apex, as seen in the ileum of the controls, was no longer detectable. In the duodenum, however, villus height remained unaltered and the in situ activity of the disaccharidases was increased at both villus sites when compared with the controls. The results indicate different effects of bile on mucosal morphology and function in the proximal and distal small intestine.
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PMID:Effects of biliary diversion to the ileum on the in situ disaccharidase activities of duodenal and ileal mucosa in the rat: a study on enzyme kinetics in tissue sections. 641


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