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)

The Streptomyces sp. beta-glucosidase (Bgl3) is a retaining glycosidase that belongs to family 1 glycosyl hydrolases. Steady-state kinetics with p-nitrophenyl beta-D-glycosides revealed that the highest k(cat)/K(M) values are obtained with glucoside (with strong substrate inhibition) and fucoside (with no substrate inhibition) substrates and that Bgl3 has 10-fold glucosidase over galactosidase activity. Reactivity studies by means of a Hammett analysis using a series of substituted aryl beta-glucosides gave a biphasic plot log k(cat) vs pK(a) of the phenol aglycon: a linear region with a slope of beta(lg) = -0.8 for the less reactive substrates (pK(a) > 8) and no significant dependence for activated substrates (pK(a) < 8). Thus, according to the two-step mechanism of retaining glycosidases, formation of the glycosyl-enzyme intermediate is rate limiting for the former substrates, while hydrolysis of the intermediate is for the latter. To identify key catalytic residues and on the basis of sequence similarity to other family 1 beta-glucosidases, glutamic acids 178 and 383 were changed to glutamine and alanine by site-directed mutagenesis. Mutation of Glu178 to Gln and Ala yielded enzymes with 250- and 3500-fold reduction in their catalytic efficiencies, whereas larger reduction (10(5)-10(6)-fold) were obtained for mutants at Glu383. The functional role of both residues was probed by a chemical rescue methodology based on activation of the inactive Ala mutants by azide as exogenous nucleophile. The E178A mutant yielded the beta-glucosyl azide adduct (by (1)H NMR) with a 200-fold increase on k(cat) for the 2,4-dinitrophenyl glucoside but constant k(cat)/K(M) on azide concentration. On the other hand, the E383A mutant with the same substrate gave the alpha-glucosyl azide product and a 100-fold increase in k(cat) at 1 M azide. In conclusion, Glu178 is the general acid/base catalyst and Glu383 the catalytic nucleophile. The results presented here indicate that Bgl3 beta-glucosidase displays kinetic and mechanistic properties similar to other family 1 enzymes analyzed so far. Subtle differences in behavior would lie in the fine and specific architecture of their respective active sites.
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PMID:Mechanism of the family 1 beta-glucosidase from Streptomyces sp: catalytic residues and kinetic studies. 1135 32

The extraction method for beta-glucosidase from green vanilla beans has been studied. The effect of storage of green beans and protein extracts on beta-glucosidase and peroxidase activity was investigated: the best method, resulting in the highest enzyme activities, particularly for glucosidase, was through extraction of very fresh green beans in the presence of BisTris propane buffer at pH 8. The best method for storage of the extracts was at -80 degrees C after addition of 15% glycerol, when over 90% of initial activity was still present. Peroxidase activity did not change in frozen beans or in frozen extracts.
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PMID:beta-Glucosidase and peroxidase stability in crude enzyme extracts from green beans of Vanilla planifolia Andrews. 1170 22

3-Hydroxykynurenine-3-O-beta-glucoside (3-HKG) functions in the primate lens as a filter of 295- 400-nm light, thereby protecting the retina from damaging UV radiation. Although extensive studies have been conducted to determine the functional role of 3-HKG in the primate lens, an efficient method for its synthesis and purification has yet to be developed. Several procedures have been reported for the synthesis of 3-HKG; however, these procedures either result in low yields or require numerous sequential reactions and purification steps. In this study, we report a two-step synthesis of 3-HKG with a one-step purification and a two- to eightfold increase in yield over previously reported methods. Additionally, an assay was developed to confirm the presence of a beta-glycosidic linkage in the purified reaction product and we propose a method by which 3-HKG can be used as a general probe of beta-glucosidase activity. The assay consists of adding glucose oxidase to the 3-HKG/glucosidase solution and then allowing the hydrogen peroxide, generated from the interaction of glucose with glucose oxidase, to oxidize 3-hydroxykynurenine to xanthomattin (XAN) and 4,6-dihydroxyquinolinequinone carboxylic acid (DHQCA). Both XAN and DHQCA absorb strongly between 400 and 500 nm and the color change of the solution can be seen by eye. In addition, XAN fluoresces in the visible region with lambda(max) = 527 nm.
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PMID:Synthesis and purification of 3-hydroxykynurenine-O-beta-glucoside, a primate lens ultraviolet filter, and its application in a two-step assay for beta-glucosidase activity. 1172 87

A seasonal study of the quantitative and qualitative distribution of heterotrophic bacterial community was carried out in the Adriatic Sea between April 1995 and January 1996, in order to evaluate its spatial and temporal variability and metabolic potential in the degradation processes of organic matter. The culturable bacteria (CFU) ranged between 0.1 and 22% of total bacterioplankton with a maximum percentage in surface samples of coastal zones. Their distribution was generally affected by the prevailing hydrological conditions. At the coastal stations about 44-75% of CFU variance could be explained by river runoff. The changes in the composition of heterotrophic bacterial community showed a seasonal succession of main bacterial groups, with a prevalence of Gram negative, non fermenting bacteria in the cold period (April-January) and an increase of Vibrionaccae and pigmented bacteria in summer. The seasonal variations were more important at the stations influenced by rivers than offshore. The bacterial community showed a greater versatility for organic polymers hydrolysis in the offshore station than in the coastal areas. Over 60% of all isolated heterotrophic bacteria expressed peptidase, lipase and phosphatase ectoenzymes activities, in all seasons and showed an increasing trend in warm period (in July October). The alpha- and beta-glucosidase potentials of bacteria were lower (20% on average) and showed different pattern during the year. These results suggest different role of the bacterial community in the decomposition of organic matter in the Adriatic Sea. Since only 20% of bacterial strains expressed glucosidase activity, carbohydrate-rich polymers such as mucilage might accumulate.
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PMID:Heterotrophic bacteria in the northern Adriatic Sea: seasonal changes and ectoenzyme profile. 1214 42

A beta-glucosidase with high specificity for podophyllotoxin-4-O-beta-D-glucopyranoside was purified from the leaves of Podophyllum peltatum. The 65-kDa polypeptide had optimum activity at pH 5.0 and was essentially inactive at pH 6.5 or above. Maximum catalytic activity of this glucosidase was obtained at 45 degrees C, but the enzyme was not heat stable. This beta-glucosidase displayed higher substrate specificity for podophyllotoxin-4-O-beta-D-glucopyranoside than for the other lignans tested, and for the (1-->3) linkage of laminaribiose than for other glucosidic linkages.
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PMID:Podophyllum peltatum possesses a beta-glucosidase with high substrate specificity for the aryltetralin lignan podophyllotoxin. 1263 23

Gaucher disease, the most common lysosomal storage disease, is caused by mutations in the gene that encodes acid-beta-glucosidase (GlcCerase). Type 1 is characterized by hepatosplenomegaly, and types 2 and 3 by early or chronic onset of severe neurological symptoms. No clear correlation exists between the approximately 200 GlcCerase mutations and disease severity, although homozygosity for the common mutations N370S and L444P is associated with non- neuronopathic and neuronopathic disease, respectively. We report the X-ray structure of GlcCerase at 2.0 A resolution. The catalytic domain consists of a (beta/alpha)(8) TIM barrel, as expected for a member of the glucosidase hydrolase A clan. The distance between the catalytic residues E235 and E340 is consistent with a catalytic mechanism of retention. N370 is located on the longest alpha-helix (helix 7), which has several other mutations of residues that point into the TIM barrel. Helix 7 is at the interface between the TIM barrel and a separate immunoglobulin-like domain on which L444 is located, suggesting an important regulatory or structural role for this non-catalytic domain. The structure provides the possibility of engineering improved GlcCerase for enzyme-replacement therapy, and for designing structure-based drugs aimed at restoring the activity of defective GlcCerase.
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PMID:X-ray structure of human acid-beta-glucosidase, the defective enzyme in Gaucher disease. 1279 54

Eberhart, Bruce (University of North Carolina, Greensboro), David F. Cross, and Lewis R. Chase. beta-Glucosidase system of Neuspora crassa. I. beta-Glucosidase and cellulose activities of mutant and wild-type strains. J. Bacteriol. 87:761-770. 1964.-A mutant strain, gluc-1, of Neurospora crassa was isolated and characterized by its low level of beta-glucosidase activity. The mutant was selected by testing irradiated colonies for extracellular beta-glucosidase activity. Strains containing the gluc-1 gene were also visibly detected by their reduced ability to destroy esculin in their growth media. The mutant strain grew at wild-type rates with cellobiose or carboxymethylcellulose as carbon sources. This auxotrophic similarity with wild type is explained by the presence of at least two beta-glucosidases (and possibly two cellulases) in Neurospora that act complementarily. The thermolabile beta-glucosidase was destroyed after 1 min of incubation at 60 C. This enzyme was present in mycelia but absent in conidial extracts. A second beta-glucosidase that is comparatively stable at 60 C was present in both mycelia and conidia. A partial separation of these enzymes was achieved with ammonium fractionation of mycelial extracts of gluc-1 and wild-type strains. Thermolabile beta-glucosidase and cellulase activity appear not to be affected by the gluc-1 mutation, whereas the thermostable glucosidase is greatly reduced in gluc-1 strains.
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PMID:BETA-GLUCOSIDASE SYSTEM OF NEUROSPORA CRASSA. I. BETA-GLUCOSIDASE AND CELLULASE ACTIVITIES OF MUTANT AND WILD-TYPE STRAINS. 1413 12

A range of new C-1 modified derivatives of the powerful glucosidase inhibitor 2,5-dideoxy-2,5-imino-D-mannitol has been synthesised and their biological activities probed with the beta-glucosidase from Agrobacterium sp. Ki values are compared with those of previously prepared close relatives. Findings suggest dramatic effects exerted by the aglycon binding site on substrate/inhibitor binding.
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PMID:Probing the aglycon binding site of a beta-glucosidase: a collection of C-1-modified 2,5-dideoxy-2,5-imino-D-mannitol derivatives and their structure-activity relationships as competitive inhibitors. 1518 33

Strictosidine beta-D-glucosidase, a plant enzyme initiating biosynthetic pathways to about 2000 monoterpenoid indole alkaloids with an extremely large number of various carbon skeletons, has been functionally expressed in Escherichia coli and purified to homogeneity in mg scale. Crystals suitable for X-ray analysis were found by robot-mediated screening. Using the hanging-drop technique, optimum conditions were 0.3 M ammonium sulfate, 0.1 M sodium acetate, pH 4.6 and PEG 4000 (10%) as precipitant buffer. The crystals of strictosidine glucosidase belong to the space group P42(1)2 with unit cell dimensions of a=157.63, c=103.59 A and diffract X-rays to 2.48-A resolution.
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PMID:Expression, purification, crystallization and preliminary X-ray analysis of strictosidine glucosidase, an enzyme initiating biosynthetic pathways to a unique diversity of indole alkaloid skeletons. 1568 Feb 42

Cellulose, a main structural constituent of plants, is the major nutritional component for wood-feeding termites. Enzymatic hydrolysis of cellulose to glucose occurs by the action of cellulases, a mixture of the three major classes of enzymes including endo-1,4-beta-glucanases, exo-1,4-beta-glucanases, and beta-glucosidase. Lower termites, such as the Formosan subterranean termite, Coptotermes formosanus Shiraki, require cellulolytic protozoa to efficiently digest cellulose for survival. Inhibitors developed against any of these cellulase system enzymes would be a potential termite treatment avenue. Our effort was to develop a screening system to determine whether termites could be controlled by administration of cellulase system inhibitors. Some reported compounds such as gluconolactone, conduritol B epoxide, and 1-deoxynojirimycin are potential beta-glucosidase inhibitors, but they have only been tested in vitro. We describe an in vivo method to test the inhibitory ability of the designated chemicals to act on beta-1,4-glucosidases, one member of the cellulase system that is the key step that releases glucose for use as an energy and carbon source for termites. Inhibition in releasing glucose from cellooligosaccharides might be sufficient to starve termites. Fluorescein di-beta-D-glucopyranoside was used as the artificial enzyme substrate and the fluorescent intensity of the reaction product (fluorescein) quantified with an automated fluorescence plate reader. Several known in vitro beta-1,4-glucosidase inhibitors were tested in vivo, and their inhibitory potential was determined. Endogenous and protozoan cellulase activities are both assumed to play a role.
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PMID:Screening method for inhibitors against formosan subterranean termite beta-glucosidases in vivo. 1576 64


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