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:3.2.1.21 (beta-glucosidase)
3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Centrifugation of homogenates of bovine retinas to isopycnic equilibrium in sucrose density gradients yielded three partially overlapping bands of particles which were, in the order of increasing density: (a) photoreceptor cell (rod) outer segments; (b) plasma membranes, lysosomes, and large fragments of endoplasmic reticulum; and (c) mitochondria. The only enzyme activity investigated which had a peak coinciding only with outer segment fractions was guanylate cyclase. Enzyme activities with peaks in both the outer segment and denser fractions included 5'-nucleotidase and cyclic GMP phosphodiesterase. Enzyme activities with peaks only in the denser fractions included sodium and potassium ion-activated ATPase ((Na+ + K+)-ATPase), adenylate cyclase, cyclic AMP phosphodiesterase, beta-glucosidase, beta-galactosidase, and succinate-dependent cytochrome c reductase. These results suggest that some of the activities once thought to be present in rod outer segments are actually present in particles from elsewhere in the retina which contaminate rod outer segment preparations.
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PMID:Distribution of enzyme activities in subcellular fractions of bovine retina. 0 65

The optimal reaction conditions and kinetic properties of eleven leukocyte acid hydrolases determined with the use of fluorigenic derivatives of 4-methyl-umbelliferone are described. The enzymes studied were acid phosphatase, aryl sulfatase, alpha- and beta-glucosidase, alpha- and beta-galactosidase, alpha-mannosidase, N-acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucuronidase and alpha-fucosidase. More than 90% of the activity of each enzyme was released into a 27,000 X g supernatant by a double sonication procedure employing 0.9% sodium chloride and 0.1% Triton X-100. The Km values obtained were similar to those previously reported for chromogenic subtrates. A single Km value could not be derived for beta-galactosidase because its double reciprocal plot was not linear. All enzymes could be measured with less than 10 mug of protein within 15 min. Activators and inhibitors studied included the chloride salts of Na+, K+, Zn2+, Ca2+, Mg2+, Hg2+, and Fe2+ as well as p-chloromercuriphenysulfonate, glutathione, BAL, EDTA, EGTA, Triton X-100 and sodium taurocholate. The reaction conditions described in this report can be used for the diagnosis of various lysosomal storage diseases and should facilitate the development of automated procedures for the analysis of these eleven enzyme activities with small quantities of blood.
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PMID:Human leukocyte acid hydrolases: characterization of eleven lysosomal enzymes and study of reaction conditions for their automated analysis. 0 26

Two isozymes of membrane-bound beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) with activity towards 4-methylumbelliferyl-beta-D-glucopyranoside have been identified in human cells. One of these isozymes was found to have a pH optimum of 5.0, a Km of 0.4 mM and to be rapidly inactivated at pH 4.0 ("acid-labile"). The second isozyme had a pH optimum of 4.5, a Km of 0.8 mM and was stable at pH 4.0 ("acid-stable"). Cultured long-term lymphoid lines and peripheral blood leukocytes contained both isozymes while cultured skin fibroblasts contained only the "acid-stable" form in detectable amounts. The specific activity of the "acid-stable" isozyme was severely reduced in cultured skin fibroblasts, cultured long-term lines and peripheral leukocytes from patients with Gaucher's disease. The specific activity of the "acid-labile" enzyme in the latter two cell types was apparently unaffected. The beta-glucosidase activity in all three cell types examined was predominantly particulate but the enzyme could be solubilized with low concentrations of Triton X-100. The solubilized enzyme required sodium taurocholate (0.2%) for maximum activity. Solubilized beta-glucosidase did not exhibit the cell-specific differences in pH optimum and Km shown by the membrane-bound enzyme.
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PMID:Cell-specific differences in membrane beta-glucosidase from normal and Gaucher cells. 1 44

Cultured human skin fibroblasts from normal and glucosylceramidotic subjects are found to contain one beta-glucoside hydrolase as compared with multiple enzymes in other tissues. The fibroblast enzyme has an approximate molecular weight of 150,000 under isotonic conditions, as determined by gel filtration. It occurs as a large aggregate at low ionic strength. Ceramide, 4-methylumbelliferyl, and p-nitrophenyl beta-glucosides are active as substrates. The enzyme in whole cell homogenates is membrane-bound and is solubilized by a combination of Triton X-100 and sodium taurocholate. It has a pH optimum at 4.2 and no demonstrable divalent cation requirement. The cultured fibroblast beta-glucosidase displays close similarity to one of the forms of beta-glucosidase in human spleen, specifically that form which is affected in Gaucher's disease. 4-Methylumbelliferyl beta-glucosidase activity in homozygous fibroblasts from infantile and adult forms of Gaucher's disease are reduced to 9 and 14%, respectively, of normal fibroblast activity. The residual activity in the lipidotic cells shows increased heat lability, but cannot be distinguished from that in normal cells with respect to gel exclusion properties, Michaelis constant, and pH dependence.
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PMID:beta-Glucoside hydrolase activity of normal and glucosylceramidotic cultured human skin fibroblasts. 1 34

We describe a new assay that is useful for identifying individuals who may be affected with Gaucher's disease. The assay involves the determination of serum acid phosphatase activity using the fluorogenic substrate 4-methylumbelliferyl phosphate. The assay measures acid phosphatase activity at pH 6.0 in the presence of 3.0 M 2-mercaptoethanol and requires a 5 microliter serum sample and a 15-min incubation period. Under these conditions, 2-mercaptoethanol preferentially inhibited the acid phosphatase activity in control serum but did not inhibit the elevated acid phosphatase present in the serum of patients with Gaucher's disease. Using this assay, we observed a 5-50-fold elevation in serum acid phosphatase activity in 8 patients with the adult, non-neuropathic form of Gaucher's disease when compared to control serum assayed under the same conditions. Serum from several heterozygotes free from pathology exhibited normal acid phosphatase activity when assayed at pH 6.0 in the presence of 2-mercaptoethanol. Acid phosphatase activity in serum from patients with prostatic cancer can be distinguished from that in Gaucher serum on the basis of the well-documented sensitivity of the former to inhibition by sodium tartrate. A serum sample from a patient with Niemann-Pick disease exhibited a mild elevation in tartrate-resistant acid phosphatase activity so that conclusive diagnosis of Gaucher's disease requires assaying leukocytes or fibroblasts from suspected patients for glucocerebroside:beta-glucosidase activity.
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PMID:Determination of serum acid phosphatase in Gaucher's disease using 4-methylumbelliferyl phosphate. 2 Feb 52

Three components (GA, GB-1, and GB-2) of beta-glucosidase were detected in the culture filtrate of Pyricularia oryzae grown in a cellulose or cellulose derivative medium. Among them, GB-1 was induced most strongly. Purified GB-1 was homogeneous on polyacrylamide gel electrophoresis and showed an approximately 1,400-fold increase of specific activity over the starting material. The molecular weight was determined to be 240,000 by sodium dodecyl sulfate-gel electrophoresis. A similar value was also obtained by sucrose density gradient centrifugation. The enzyme contained a high proportion of acidic amino acids and mannose, and the isoelectric point of the enzyme was pH 4.15. The enzyme had a pH optimum of 5.5 and a temperature optimum at 55 degrees C. beta-Glucosidase activity was inhibited by Mn2+, Cu2+, Hg2+, p-chloromercuribenzoate, and glucono-delta-lactone. The enzyme split off glucose units one by one from the nonreducing ends of not only beta-glucooligosaccharides but also some beta-glucans, such as carboxymethylcellulose, laminaran, pustulan, and zeagallan. The affinity for cello- and laminari-oligosaccharides tended to increase in parallel with the chain length.
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PMID:Studies on cellulases of a phytopathogenic fungus, Pyricularia oryzae cavara. II. Purification and properties of a beta-glucosidase. 2 39

1. Rat liver cells obtained by dispersion with collagenase were used to investigate the mode of entry of L-tri-iodothyronine into the cell. 2. The hormone was taken up very rapidly at 23 degrees C; the linear phase of uptake lasted for up to approx. 20 s. 3. A plot of the initial rates of uptake against different concentrations of L-tri-iodothyronine yielded a sigmoidal curve. The Eadie--Hofstee plot (v/[S]2 versus v) yielded two straight lines. The uptake component with an apparent Kt value of 86 +/- 15 pM was designated as system I, and the second uptake component with an apparent Kt of 726 +/- 11 pM as system II. The Hill plot for system I was not linear; the apparent Hill coefficient for system II was calculated to be 2.1.4. Uptake of L-tri-iodothyronine by system I was higher at pH 6.4 than at pH 7.4; system II was relatively insensitive to changes in the pH of the external medium. 5. Both systems exhibited a transition temperature at about 16 degrees C in the Arrhenius plot. The activation energies of the two systems below and above 16 degrees C were 72.8 and 47.7 and 54.4 and 33.1 J/mol respectively. 6. Inhibitors of cellular energy reduced the uptake by system I to a larger extent than that by system II. 7. Replacement of Na+ in the external medium by either K+ or choline led to uptake that followed normal Michaelis--Menten kinetics. 8. Thiol-group-blocking agents reduced the uptake of the hormone by both systems. 9. Treatment of liver cells with beta-glucosidase, Pronase and neuraminidase led to a decrease in the uptake of L-tri-iodothyronine by system I, whereas uptake by system II was decreased after treatment with phospholipase A2, beta-galactosidase. Pronase and neuraminidase. 10. The stereoisomer D-tri-iodothyronine (100--3000 pM) did not affect system I, but uptake by system II decreased with increasing concentration of D-tri-iodothyronine. Reverse L-tri-iodothyronine (2--100 pM) and L-thyroxine (100--3000 pM) did not influence uptake by either system. 11. Under identical conditions of incubation, the uptake of L-tri-iodothyronine was 3.7 times higher than binding to cytosol proteins. The binding was insensitive to metabolic inhibitors. The results suggest that cytosol proteins are not directly involved in the uptake of L-tri-iodothyronine. 12. Plasma-membrane vesicles also take up the hormone rapidly at 23 degrees C. Increasing the osmolarity of the external medium led to a decrease in the uptake of L-tri-iodothyronine by vesicles. 13. Uptake as a function of L-tri-iodothyronine concentration exhibited a sigmoidal curve. The Eadie--Hofstee plot showed two uptake components with apparent Kt values of 96.8 and 1581 pM. 14. The results of our study are consistent with a carrier-mediated translocation of the hormone into the cell.
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PMID:Uptake of L-tri-iodothyronine by isolated rat liver cells. A process partially inhibited by metabolic inhibitors; attempts to distinguish between uptake and binding to intracellular proteins. 4 20

A second extracellular beta-glucosidase (betalarge) of Aspergillus fumigatus was purified to homogeneity and shown to be a glycoprotein, as determined by polyacrylamide gel electrophoresis followed by staining for protein and for carbohydrate. Its molecular weight was approximately 340,000 by gel filtration, while sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave an apparent molecular weight of 170,000, suggesting that the enzyme has two subunits. The glucosidase contained covalently bound sugars consisting of about 2 mol of glucosamine and 16 mol of mannose per mol of protein. The carbohydrate was found to be attached to the peptide via glucosaminyl leads to peptide linkage, possibly to asparagine residues. At pH 4.5 this enzyme readily hydrolyzed p-nitrophenyl-beta-D-glucopyranoside (Km = 0.88 mM) and cleaved two glucose disaccharides: gentiobiose (beta,1 leads to 6; Km = 0.75 mM) and cellobiose (beta,1 leads to 4; Km = 0.84 mM). Although its activity is similar to that of a previously purified beta-glucosidase (betasmall), the two enzymes differ with respect to their pH activity profiles, substrate specificities, and molecular weights. Also double diffusion tests with anti-betasmall antiserum and both purified beta-glucosidases revealed a nonidentical cross-reaction. Microcomplement fixation of native and periodate-oxidized betasmall suggested that the oligosaccharide chain(s) was not a major antigenic site.
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PMID:Glycoprotein enzymes secreted by Aspergillus fumigatus: purification and properties of a second beta-glucosidase. 5 48

Dog enterocyte brush border proteins have been studied after a 75% proximal resection of the small bowel. This study was carried on microvillar membrane preparations purified from ileal mucosa sampled before and after regeneration on neighbouring intestinal segments, each animal acting as its own control. After six weeks of regeneration a statistically significant decrease of the following enzyme specific activities was observed: lactase, cellobiase, maltase, sucrase, palatinase, dextranase, trehalase, alkaline phosphatase, aminopeptidase and gamma-glutamyl transferase. Analysis of brush border proteins by polyacrylamide gel electrophoresis in presence of sodium dodecyl sulphate have shown after regeneration a decreased rate for the proteins with a molecular weight higher than 100,000 daltons. Modifications of electrophoretic patterns seem to be related to the specific activity decreases observed for brush border enzymes after regeneration, since the molecular weight of these enzymes were found between 116,000 and 285,000 daltons, after gel filtration.
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PMID:Effect of massive proximal small bowel resection on intestinal brush border membrane proteins in the dog. 8 27

Membrane-bound beta-glucosidase from cultured skin fibroblasts can be solubilized in an active form by treatment of membrane preparations with a mixture of Triton X-100 and sodium taurocholate. Several properties of the solubilized enzyme have been studied in fibroblasts from normal, healthy individuals and from 14 patients with different clinical forms of Gaucher disease. The patients studied were classified as follows: group 1 consisted of 10 chronic patients, all (with one exception) of Ashkenazi Jewish origin; group 2 consisted of three black American patients with severe visceral symptoms, manifest from early childhood, but with no apparent neurological involvement; and group 3 consisted of a single white patient with the classical infantile form of the disease. Specific beta-glucosidase activity ranged from 6.6% to 16.5% mean control value in group 1 patients and from 4.1% to 5.8% in groups 2 and 3. When compared with the enzyme from control fibroblasts, the enzyme from chronic Gaucher patients (group 1) was more rapidly inactivated at 50 degrees C, had an altered pH curve, was less effectively inhibited by deoxycorticosterone-beta-glucoside, and was more effectively inhibited by deoxycorticosterone. The enzyme from patients in groups 2 and 3 was qualitatively indistinguishable from the control enzyme in terms of these parameters. No differences in Km (4-methylumbelliferyl-beta-glucoside) or sedimentation coefficient were found between the beta-glucosidases from control and Gaucher cells. The results demonstrate that cells from Ashkenazi Jewish patients with the chronic form of Gaucher disease contain a structurally altered form of beta-glucosidase. This enzyme differs both from normal beta-glucosidase and from the residual enzyme in patients of different ethnic origin and with clinically more severe forms of the disease.
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PMID:Properties of beta-glucosidase in cultured skin fibroblasts from controls and patients with Gaucher disease. 10 89


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