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)

A beta-D-glycosidase activity was purified from mycelium of Humicola grisea var. thermoidea grown on avicel as the main carbon source. The purified enzyme was a glycoprotein and migrated as a single polypeptide band on polyacrylamide gel electrophoresis under native or denaturing conditions. The apparent molecular weight of the enzyme was estimated to be 55 kDa by gel filtration and SDS-PAGE. The enzyme was active against o-nitrophenyl beta-D-galactoside; p-nitrophenyl beta-D-glucoside, p-nitrophenyl beta-D-fucoside, lactose and cellobiose, PNP fucoside (synthetic substrate) and cellobiose (natural substrate) being the best utilized. A comparison of the properties of beta-D-galactosidase, beta-D-glucosidase and beta-D-fucosidase showed that three activities exhibited similar pH and temperature optima and the same thermostability. The hydrolysis rate of substrate mixtures suggests that the enzyme possesses a common catalytic site for all the substrates assayed.
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PMID:Beta-D-glycosidase activities of Humicola grisea: biochemical and kinetic characterization of a multifunctional enzyme. 210 72

Human lysosomal beta-glucosidase (D-glucosyl-acylsphingosine glucohydrolase, EC 3.2.1.45) is a membrane-associated enzyme that cleaves the beta-glucosidic linkage of glucosylceramide (glucocerebroside), its natural substrate, as well as synthetic beta-glucosides. Experiments with cultured cells suggest that in vivo this glycoprotein requires interaction with negatively charged lipids and a small acidic protein, SAP-2, for optimal glucosylceramide hydrolytic rates. In vitro, detergents (Triton X-100 or bile acids) or negatively charged ganglioside or phospholipids and one of several "activator proteins" increase hydrolytic rate of lipid and water-soluble substrates. Using such in vitro assay systems and active site-directed covalent inhibitors, kinetic and structural properties of the active site have been elucidated. The defective activity of this enzyme leads to the variants of Gaucher disease, the most prevalent lysosomal storage disease. The nonneuronopathic (type 1) and neuronopathic (types 2 and 3) variants of this inherited (autosomal recessive) disease but panethnic, but type 1 is most prevalent in the Ashkenazi Jewish population. Several missense mutations, identified in the structural gene for lysosomal beta-glucosidase from Gaucher disease patients, are presumably casual to the specifically altered posttranslational oligosaccharide processing or stability of the enzyme as well as the altered in vitro kinetic properties of the residual enzyme from patient tissues.
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PMID:Acid beta-glucosidase: enzymology and molecular biology of Gaucher disease. 212 41

Mannostatin A is a metabolite produced by the microorganism Streptoverticillium verticillus and reported to be a potent competitive inhibitor of rat epididymal alpha-mannosidase. When tested against a number of other arylglycosidases, mannostatin A was inactive toward alpha- and beta-glucosidase and galactosidase as well as beta-mannosidase, but it was a potent inhibitor of jack bean, mung bean, and rat liver lysosomal alpha-mannosidases, with estimated IC50's of 70 nM, 450 nM, and 160 nM, respectively. The type of inhibition was competitive in nature. This compound also proved to be an effective competitive inhibitor of the glycoprotein-processing enzyme mannosidase II (IC50 of about 10-15 nM with p-nitrophenyl alpha-D-mannopyranoside as substrate, and about 90 nM with [3H]mannose-labeled GlcNAc-Man5GlcNAc as substrate). However, it was virtually inactive toward mannosidase I. The N-acetylated derivative of mannostatin A had no inhibitory activity. In cell culture studies, mannostatin A also proved to be a potent inhibitor of glycoprotein processing. Thus, in influenza virus infected Madin Darby canine kidney (MDCK) cells, mannostatin A blocked the normal formation of complex types of oligosaccharides on the viral glycoproteins and caused the accumulation of hybrid types of oligosaccharides. This observation is in keeping with other data which indicate that the site of action of mannostatin A is mannosidase II. Thus, mannostatin A represents the first nonalkaloidal processing inhibitor and adds to the growing list of chemical structures that can have important biological activity.
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PMID:Mannostatin A, a new glycoprotein-processing inhibitor. 227 38

Australine [(1R,2R,3R,7S,7aR)-3-(hydroxymethyl)-1,2,7-trihydroxypyrrolizid ine] is a polyhydroxylated pyrrolizidine alkaloid that was isolated from the seeds of the Australian tree Castanospermum australe and characterized by NMR and X-ray diffraction analysis [Molyneux et al. (1988) J. Nat. Prod. (in press)]. Since swainsonine and catanospermine are polyhydroxylated indolizidine alkaloids that inhibit specific glycosidases, we tested australine against a variety of exoglycosidases to determine whether it would inhibit any of these enzymes. This alkaloid proved to be a good inhibitor of the alpha-glucosidase amyloglucosidase (50% inhibition at 5.8 microM), but it did not inhibit beta-glucosidase, alpha- or beta-mannosidase, or alpha- or beta-galactosidase. The inhibition of amyloglucosidase was of a competitive nature. Australine also inhibited the glycoprotein processing enzyme glucosidase I, but had only slight activity toward glucosidase II. When incubated with cultured cells, this alkaloid inhibited glycoprotein processing at the glucosidase I step and caused the accumulation of glycoproteins with Glc3Man7-9(GlcNAc)2-oligosaccharides.
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PMID:Australine, a pyrrolizidine alkaloid that inhibits amyloglucosidase and glycoprotein processing. 249 72

Two forms of the beta-glucosidase amygdalin hydrolase (AH I and II), which catalyze the hydrolysis of (R)-amygdalin to (R)-prunasin and D-glucose, have been purified over 200-fold from mature black cherry (Prunus serotina Ehrh.) seeds. These proteins showed very similar molecular and kinetic properties but could be resolved by chromatofocusing and isoelectric focusing. AH I and II were monomeric (Mr 60,000) and had isoelectric points of 6.6 and 6.5, respectively. Their glycoprotein character was indicated by positive periodic acid-Schiff staining and by their binding to concanavalin A-Sepharose 4B with subsequent elution by alpha-Me-D-glucoside. Of the natural glycosidic substrates tested, both enzymes showed a pronounced preference for the endogenous cyanogenic disaccharide (R)-amygdalin. They also hydrolyzed at the same active site the synthetic substrates p-nitrophenyl-beta-D-glucoside and 4-methylumbelliferyl-beta-D-glucoside but were inactive towards (R)-prunasin, p-nitrophenyl-alpha-D-glucoside, and 4-methylumbelliferyl-alpha-D-glucoside. Maximum hydrolytic activity was shown in citrate-phosphate buffer in the pH range 4.5-5.0. AH I and II were inhibited competitively by the reaction product (R)-prunasin and noncompetitively (mixed type) by delta-gluconolactone and castanospermine.
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PMID:Comparison of kinetic and molecular properties of two forms of amygdalin hydrolase from black cherry (Prunus serotina Ehrh.) seeds. 308 90

Affinity chromatography of a commercial preparation of beta-glucosidase from Aspergillus niger using concanavalin A-Sepharose (CAS) was employed as a means of purifying this glycoprotein. However, mannose (up to 1.08 M) was ineffective as an eluent of this enzyme from CAS, as were several other sugars and their derivatives, including 0.5 M glucose. Also, washing the CAS: beta-glucosidase complex with buffer at pH 3.5 in the absence of MnCl2 and CaCl2 (required to preserve the binding activity of concanavalin A below pH 5.0) did not result in elution of this enzyme. On the contrary, endoglucanase activity present in a crude cellulase complex (A. niger) which bound to CAS could be eluted by mannose (0.5-0.7 M) and was fractionated into at least two components. The CAS: beta-glucosidase complex hydrolyzed cellobiose to glucose and possessed an activity of 2,158 units/g dry CAS. It could be used, therefore, for continuous cellobiose hydrolysis without leakage of enzyme from the support.
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PMID:Affinity chromatography of beta-glucosidase and endo-beta-glucanase from Aspergillus niger on concanavalin A-Sepharose: implications for cellulase component purification and immobilization. 310 Oct 58

Extracellular cellulolytic enzymes produced by a species of Monilia could be fractionated by chromatography on SP-Sephadex, Con A-Sepharose, and cellobiose-Sepharose. These methods did not separate the beta-D-glucosidases (beta-D-glucoside glucohydrolases, EC 3.2.1.21) from the cellulases and xylanases within a single purification step. Fractionation by isoelectric focusing on a flat-bed granulated gel gave all of the beta-D-glucosidase activity in a single zone isoelectric at pH 8-9. The beta-D-glucosidase could be further purified to homogeneity by column isoelectric focusing at pH 8.0-10.5, and gel filtration on Biogel P-100. The purified beta-D-glucosidase showed optimal activity at pH 4-5 and 50 degrees, was isoelectric at pH 8.87, and had a molecular weight of 46,600. SDS-Polyacrylamide-gel electrophoresis demonstrated that the beta-D-glucosidase was not dissociated into subunits and, hence, consisted of a single polypeptide chain. The enzyme is considered a glycoprotein, as it binds to Con A-Sepharose. The beta-D-glucosidase hydrolyzed (1----2)-, (1----4)-, and (1----6)-beta-D-glucosidic linkages but not cellulose. Nitrophenyl beta-D-glucopyranosides and beta-D-xylopyranosides were also degraded. The beta-D-glucosidase was competitively inhibited by D-glucose (Ki 0.67 mM).
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PMID:Fractionation of the cellulolytic enzymes produced by a species of Monilia; purification and properties of an extracellular beta-D-glucosidase. 310 61

The chemical synthesis of swainsonine [(1S,2R,8R,8 alpha R)-trihydroxyindolizidine] from trans-1,4-dichloro-2-butene was previously described [Adams, C. E., Walker, F. J., & Sharpless, K. B. (1985) J. Org. Chem. 50, 420-424]. A modification of that synthesis provided two other isomers, referred to here as "Glc-swainsonine" [(1S,2S,8R,8 alpha R)-trihydroxyindolizidine] and "Ido-swainsonine" [(1S,2S,8S,8 alpha R)-trihydroxyindolizidine]. To determine whether these new compounds had biological activity, they were compared to swainsonine as inhibitors of a number of commercially available glycosidases. While swainsonine is a potent inhibitor of jack bean alpha-mannosidase but does not inhibit other glycosidases, its two isomers were inactive on alpha-mannosidase but did inhibit other enzymes. Thus, Glc-swainsonine was an inhibitor of the fungal alpha-glucosidase amyloglucosidase, and this inhibition was of a competitive nature (Ki = 5 X 10(-5) M) with respect to the substrate p-nitrophenyl alpha-D-glucopyranoside. This alkaloid also inhibited beta-glucosidase, but much less effectively than alpha-glucosidase. On the other hand, Ido-swainsonine was more effective toward beta-glucosidase than toward alpha-glucosidase, and this inhibition was also of a competitive nature. None of these inhibitors were effective against beta-mannosidase or alpha- or beta-galactosidase. Glc-swainsonine was also tested against the glycoprotein processing glycosidases. Surprisingly, in this respect, the alkaloid was like swainsonine in that it inhibited mannosidase II but had no effect or only slight effect on glucosidase I, glucosidase II, and mannosidase I. Glc-swainsonine also inhibited glycoprotein processing in cell culture.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of isomers of swainsonine on glycosidase activity and glycoprotein processing. 311 29

The beta-glucosidase, linamarase, which specifically hydrolyzes cyanogenic substrates, linamarin and lotaustralin, in white clover, is synthesized in the early stages of leaf and seedling development in genetically competent plants. Plants, from natural populations, possessing at least one Li allele synthesize linamarase but plants with only li alleles do not, nor do they produce inactive but antigenically related linamarase. Linamarase is known to be a mannosyl glycoprotein, which in its active form is a dimer, with a subunit size of 62,000 Mr. We demonstrate that the antibiotic tunicamycin, which prevents N-acetyl-asparagine linked glycosylation, reduces in vivo synthesis of linarmarase. In vitro translation of mRNA from a Li Li plant yields a 59,000 Mr immunoprecipitated linamarase polypeptide which is modified to a 62,000 Mr product by the addition of dog pancreas microsomes. No anti-linamarase immunoprecipitable product is obtained from the in vitro translation products of mRNA from a li li plant.
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PMID:Synthesis of the cyanogenic beta-glucosidase, linamarase, in white clover. 312 57

The murine lymphocyte function-associated antigen 1 (LFA-1) is a glycoprotein heterodimer consisting of an Mr 180,000 alpha-chain and an Mr 95,000 beta-chain. Although LFA-1 has been studied extensively in the past few years due to its involvement in various antigen-specific T lymphocyte responses, virtually nothing is known about its glycosylation. In this report, we have analyzed the oligosaccharide moieties of the murine LFA-1 molecule. Utilizing a T lymphoma cell line, EL-4, it was found that [35S] sulfate, [3H]glucosamine, [3H]mannose, and [3H]fucose were incorporated into both the alpha- and beta-chains of LFA-1. Isolated alpha- and beta-chains from anti-LFA-1 immunoprecipitates of [3H]glucosamine-labeled NP-40 lysates were subjected to tryptic-chymotryptic digestion, and the resulting glycopeptides were fractionated by reverse-phase high performance liquid chromatography. Five major [3H]glucosamine-labeled glycopeptides were generated by this procedure from each of the two polypeptide chains. Treatment of the individual glycopeptides with almond emulsin peptide:N-glycosidase or Endo F demonstrated that the [3H]glucosamine label existed almost entirely in N-linked oligosaccharide structures (Mr 5000 to 10,000). By using similar techniques, the majority of the [35S]sulfate moieties were also found covalently bound to N-linked oligosaccharides. In addition, both [35S]sulfate-labeled alpha- and beta-chains were susceptible to Keratanase and endo-beta-galactosidase digestions, indicating the presence of sulfated N-acetyllactosamine sequences. The expression of [35S]sulfate-labeled LFA-1 on various cell types was also examined. LFA-1 was found to be sulfated only on thymocytes and splenic T cells, but not on macrophages, splenic B, or bone marrow cells.
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PMID:Lymphocyte function-associated antigen 1 (LFA-1) contains sulfated N-linked oligosaccharides. 388 93


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