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 2,3,4,6-tetra-O-benzyl-1-O-(N-benzyloxycarbonyltripeptidyl)-D-glucopyranoses ), 8, and 13 were synthesised from 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranose and the active esters of the appropriate N-protected tripeptides (Gly-Cly-Gly-, L-Phe-Gly-Gly-, and Gly-Gly-L-Phe-) in the presence of imidazole; the anomeric mixtures were resolved and the alpha and beta anomers characterised. The beta anomer of 13, containing the L and D enantiomers (ratio approximately 3:1) of Gly-Gly-Phe- as the aglycon, could be resolved by column chromatography into the pure isomeric forms. Catalytic hydrogenolysis of the beta anomers, in the presence and absence of a strong acid, yielded the free 1-esters 2 beta, 9 beta, and 14 beta, which were characterised as the monoxalate or trifluoroacetate salts and as free bases. Similarly, the alpha anomers afforded 2 alpha, 9 alpha, and 14 alpha, whereas omission of the strong acid led to accompanying 1 leads to 2 acyl migration, to give the 2-O-acyl derivatives. All of the compounds prepared were converted into the N-acetyl and/or peracetylated derivatives. The 1-esters 2 beta and 9 beta, both in the charged and uncharged form, and the trifluoroacetate salt of 14 beta, are susceptible to cleavage by beta-D-glucosidase; the enzyme had no effect on the uncharged form of 14 beta. This difference between 14 beta and its salt is discussed in conformational terms.
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PMID:Synthesis, properties, and reactions of alpha- and beta-D-glucopyranosyl esters of some tripeptides. 677 1

Three fluorometric leukocyte beta -glucosidase assays were compared for their ability to diagnose Gaucher's disease and identify carriers of the disorder: the acid beta-glucosidase assay of Beutler and Kuhl [2], a pH 5.5-sodium taurocholate-dependent assay and a new procedure which employs conduritol B epoxide, an active-site specific inhibitor of glucocerebrosidase. All three assays unambiguously identified patients with Gaucher's disease. With regard to identifying carriers the bile salt dependent assay of Peters et al. and the conduritol B epoxide-dependent procedure gave the greatest discrimination between the mean beta-glucosidase values for the control and heterozygote samples when evaluated using Student's t test. The most reliable assay for the identification of the carrier state was the conduritol B epoxide-dependent procedure which can be expected to provide the fewest false negative results when classifying heterozygotes (5%). However, the fact that none of these methods will completely separate control and heterozygote samples indicates that their use in screening programs will result in a significant number of incorrect assignments.
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PMID:An improved fluorometric leukocyte beta-glucosidase assay for Gaucher's disease. 679 54

This report describes a reliable and reproducible method for the identification of carriers of Type I Gaucher disease using blood platelets as the source of beta-glucosidase and 4-methylumbelliferyl-beta-D-glucoside as substrate. Platelet lysates have at least two identifiable beta-glucosidase activities with the synthetic substrate. One is maximally active at pH 5.0 in the absence of sodium taurocholate and the other at pH 5.6 in the presence of taurocholate. In platelets of Gaucher homozygotes and heterozygotes, the beta-glucosidase activity at pH 5.6 with the bile salt is reduced whereas the activity at pH 5.0 is the same in non-carriers, carriers and affected patients. In addition to differences in specific activity, the ratio of beta-hexosaminidase to beta-glucosidase activities is a useful parameter in the evaluation of the carrier state. Since carriers have normal activity of hexosaminidase and a reduced activity of beta-glucosidase, their mean activity ratio is about 70% higher than in non-carriers. Therefore we propose that the specific activity of beta-glucosidase at pH 5.6 in the presence of sodium taurocholate with the ratio of beta-hexosaminidase to beta-glucosidase serve as useful and reliable indices in the evaluation of the carrier state for Gaucher disease.
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PMID:Heterozygote detection of type I Gaucher disease using blood platelets. 679 62

The outer membrane (OM) of Fibrobacter succinogenes was isolated by a combination of salt, sucrose, and water washes from whole cells grown on either glucose or cellulose. The cytoplasmic membrane (CM) was isolated from OM-depleted cells after disruption with a French press. The OM and membrane vesicles isolated from the extracellular culture fluid of cellulose-grown cells had a higher density, much lower succinate dehydrogenase activity, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles different from those of the CM. The OM from both glucose- and cellulose-grown cells and the extracellular membrane vesicles from cellulose-grown cultures exhibited higher endoglucanase, xylanase, and acetylesterase activities than the CM and other cell fractions. Endoglucanase 2 was absent from the isolated OM fractions of glucose- and cellulose-grown cells and from the extracellular membrane vesicles of cellulose-grown cells but was present in the CM and intracellular glycogen granule fractions, while endoglucanase 3 was enriched in the OM. Cellobiosidase was located primarily in the periplasm as previously reported, while cellobiase was mainly present in the glycogen granule fraction of glucose-grown cells and in a nongranular glycogen and CM complex in cellulose-grown cells. The cellobiase was not eluted from glycogen granules by cellobiose, maltose, and maltotriose nor from either the granules or the cell membranes by nondenaturing detergents but was eluted from both glycogen granules and cell membranes by high concentrations of salts. The eluted cellobiase rebound almost quantitatively when diluted and mixed with purified glycogen granules but exhibited a low affinity for Avicel cellulose. Thus, we have documented a method for isolation of OM from F. succinogenes, identified the OM origin of the extracellular membrane vesicles, and located glycanases and cellobiase in membrane and glycogen fractions.
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PMID:Separation of outer and cytoplasmic membranes of Fibrobacter succinogenes and membrane and glycogen granule locations of glycanases and cellobiase. 822 22

Recent work in the synthesis of cyclic phosphonate analogues of glucose [Darrow, J.W.; Drueckhammer, D.G. (1994) J. Org. Chem. 1994, 59, 2976] has been extended to the synthesis of a corresponding phosphonamidate analogue. A phosphonate salt, phosphonate methyl ester, and phosphonamidate analogue were tested as inhibitors of two inverting alpha-glycosidases, (trehalase and glucoamylase), and two retaining glycosidases, (alpha-glucosidase and beta-glucosidase). No inhibition of any of these enzymes was observed with the phosphonate salt or methyl ester. However, the phosphonamidate gave moderate competitive inhibition of the two inverting glycosidases and the retaining alpha-glucosidase but no inhibition of beta-glucosidase. The phosphonamidate showed enhanced binding relative to a simple monosaccharide only with the inverting glycosidases. This enhanced binding is believed to be due to hydrogen bonding interactions between the phosphonamidate group and two active site carboxylate residues implicated in catalysis. The selectivity toward inverting glycosidases is consistent with differences in distance of an active site carboxylate from the anomeric carbon of the glycoside substrate for the inverting versus the retaining glycosidases.
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PMID:A cyclic phosphonamidate analogue of glucose as a selective inhibitor of inverting glycosidases. 887 56

As a first step in the development of a reporter system for gene expression in halophilic archaea, a beta-galactosidase was purified 140-fold from Haloferax alicantei (previously phenon K, strain Aa2.2). An overproducing mutant was first isolated by UV mutagenesis and screening on agar plates containing X-Gal substrate. Cytoplasmic extracts of the mutant contained 25-fold higher enzyme levels than the parent. Purification of the active enzyme was greatly facilitated by the ability of sorbitol to stabilise enzyme activity in the absence of salt, which allowed conventional purification methods (e.g., ion-exchange chromatography) to be utilised. The enzyme was optimally active at 4 M NaCl and was estimated to be 180 +/- 20 kDa in size, consisting of two monomers (each 78 +/- 3 kDa). It cleaves several different beta-galactoside substrates such as ONP-Gal, X-Gal and lactulose, but not lactose, and also has beta-D-fucosidase activity. No beta-glucosidase, beta-arabinosidase or beta-xylosidase activity could be detected. The amino-acid sequence at the N-terminus and of four proteolytic products has been determined.
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PMID:Purification and analysis of an extremely halophilic beta-galactosidase from Haloferax alicantei. 904 5

The marine rotifer, Brachionus plicatilis, is able to digest Chlorella efficiently, suggesting that the rotifer contains a powerful cellulolytic enzyme system. A multi-component cellulolytic complex, including endoglucanase (CM-cellulase), cellobiohydrolase and beta-glucosidase, was found in Brachionus plicatilis. Endoglucanase (endo-beta-1,4 glucanase) was purified to homogeneity from rotifer homogenates using a sequential chromatographic method. The purified enzyme exhibits a strong hydrolytic activity with carboxymethyl(CM)-cellulose. The optimum temperature and pH for the endoglucanase activity were 37 degrees C and 7.0, respectively. 80% of the CM-cellulase activity was retained in salt mixture that ranged from 150 to 500 mM NaCl equivalent. The purified protein was isolated with a molecular weight of approximately 62 kDa estimated by SDS-polyacrylamide gel electrophoresis.
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PMID:Purification and characterization of an endoglucanase from the marine rotifer, Brachionus plicatilis. 935 Mar 31

Carboxymethylcellulase (CMCase) was extracted and purified from an angiosperm parasite Cuscuta reflexa free from beta-glucosidase and other enzyme activities. The molecular mass and Stokes' radius of the purified enzyme are 144 kDa and 44 A, respectively. The diffusion coefficient and frictional ratio of the enzyme were 5.15 x 10(-7) cm2/sec and 1.27. The SDS-PAGE revealed homotetrameric nature of the enzyme with a subunit molecular mass of 35 +/- 1 kDa. Titration against DTNB and NBS revealed 19 sulfhydryl groups and 8 tryptophan groups, respectively, per mole of the enzyme. A sharp pH optimum at 5.0 was obtained. Cuscuta CMCase activity is unique amongst plant endoglucanases in being stimulated by Mg2+ and Mn2+ ions and by various thiols. Reaction product analysis, mode of enzyme action and substrate specificity test suggest the endo- nature of the purified CMCase. The enzyme showed K(m) value of 26 +/- 1 mg/ml for carboxymethylcellulose (sodium salt).
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PMID:Physico-chemical and functional characterization of a high molecular weight carboxymethylcellulase from Cuscuta reflexa. 949 45

The increasing development of the biotechnology industry demands the design of enzymes suitable to be used in conditions that often require broad resistance against adverse conditions. beta-glucosidase A from Bacillus polymyxa is an interesting model for studies of protein engineering. This is a well-characterized enzyme, belonging to glycosyl hydrolase family 1. Its natural substrate is cellobiose, but is also active against various artificial substrates. In its native state has an octameric structure. Its subunit conserves the general (alpha/beta)8 barrel topology of its family, with the active site being in a cavity defined along the axis of the barrel. Using random-mutagenesis, we have identified several mutations enhancing its stability and it was found that one them, the E96K substitution, involved structural changes. The crystal structure of this mutant has been determined by X-ray diffraction and compared with the native structure. The only difference founded between both structures is a new ion pair linking Lys96 introduced at the N-terminus of helix alpha2, to Asp28, located in one of the loops surrounding the active-site cavity. The new ion pair binds two segments of the chain that are distant in sequence and, therefore, this favorable interaction must exert a determinant influence in stabilizing the tertiary structure. Furthermore, analysis of the crystallographic isotropic temperature factors reveals that, as a direct consequence of the introduced ion pair, an unexpected decreased mobility of secondary structure units of the barrel which are proximal to the site of mutation is observed. However, this effect is observed only in the surrounding of one of the partners forming the salt bridge and not around the other. These results show that far-reaching effects can be achieved by a single amino acid replacement within the protein structure. Consequently, the identification and combination of a few single substitutions affecting stability may be sufficient to obtain a highly resistant enzyme, suitable to be used under extreme conditions.
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PMID:Structural basis of increased resistance to thermal denaturation induced by single amino acid substitution in the sequence of beta-glucosidase A from Bacillus polymyxa. 984 40

The influence of water potential on linear mycelial growth, secretion, and the in vitro activities of enzymes beta-glucosidase, cellobiohydrolase, beta-xylosidase, exochitinase, and chymotrypsin of Trichoderma harzianum strain T66 was studied at different temperatures. Nearly linear correlation was found between water potential and colony growth rate at both 25 degrees C and 10 degrees C, with higher growth rates at the higher temperature and higher water potentials. The amounts of enzyme secretion depended on the water potential and not on the quality of salt (NaCl or KCl) used as osmoticum. Enzyme activities were significantly affected by water potential. Significant enzyme activities were measured for most of the enzymes even at -14.800 megapascal (MPa), which is below the water potential where mycelial growth ceased. These results suggest the possibility of using mutants with improved xerotolerance for biocontrol purposes in soils with lower water potentials.
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PMID:Influence of water potential on growth, enzyme secretion and in vitro enzyme activities of Trichoderma harzianum at different temperatures. 1070 61


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