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 beta-glucosidases (EC 3.2.1.21) of Neurospora crassa were studied with respect to their location in conidia and young mycelia. Aryl-beta-glucosidase of conidia was nearly equally divided between extracellular and bound activity. Bound aryl-beta-glucosidase was almost all available to substrate. An induction procedure was used to maximize both beta-glucosidases in 4 to 6-hr cells. Aryl-beta-glucosidase was entirely bound but still mostly (90%) detectable, whereas cellobiase was mostly internal and cryptic. A freeze-thaw cycle or treatment with phenethyl alcohol or deoxycholic acid made the cellobiase detectable without releasing it from the cell. A 10 to 20% increase in cell-bound aryl-beta-glucosidase could be obtained by this treatment. Dilute HCl (0.1 n) destroyed the patent aryl-beta-glucosidase but not the cryptic aryl-beta-glucosidase or the cryptic cellobiase activity in intact cells. This suggested that most aryl-beta-glucosidase activity was exterior to the cell membrane but still within the mural space. The thermal stability of patent aryl-beta-glucosidase and released cellobiase was found to be higher than in corresponding cell-free extracts. Measurements of K(m) suggested a slightly lower affinity for substrate p-nitrophenyl-beta-d-glucopyranoside by the enzymes in intact cells compared to enzymes in extracts.
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PMID:Localization of the beta-glucosidases in Neurospora crassa. 541 19

Coated vesicles from calf brain and rat liver contain cryptic receptors which recognize and bind lysosomal enzymes via mannose 6-phosphate residues on oligosaccharide side chains (Campbell, C. H., Fine, R. E., Squicciarini, J., and Rome, L. H. (1983) J. Biol. Chem. 258, 2628-2633). In addition to mannose 6-phosphate receptors, we now report that coated vesicles from calf brain and rat liver contain the lysosomal enzymes alpha-L-fucosidase, beta-galactosidase, beta-glucosidase, beta-hexosaminidase, alpha-L-iduronidase, and alpha-mannosidase. Enzyme activities co-migrated with coated vesicles purified by agarose gel electrophoresis. Treatment of intact coated vesicles with pronase (0.05 mg/ml) had little effect on lysosomal enzyme activities, whereas a similar treatment of coated vesicles in the presence of 0.045% taurodeoxycholate resulted in the loss of most of the enzyme activities. Addition of 10 mM mannose 6-phosphate to disrupted liver coated vesicles specifically displaced up to 80% of the cryptic lysosomal enzyme activity. Disrupted liver coated vesicles and highly purified liver lysosomes were treated with anti-beta-hexosaminidase A and anti-beta-galactosidase antibodies and immunoprecipitates were analyzed by polyacrylamide gel electrophoresis. High molecular weight bands were present in the coated vesicle immunoprecipitates which were not present in the lysosome immunoprecipitates. The data suggest that coated vesicles contain mannose 6-phosphate receptor-bound lysosomal enzymes, some of which are of a higher molecular weight form. These higher molecular weight forms may represent newly synthesized enzymes that are en route to lysosomes.
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PMID:Coated vesicles from rat liver and calf brain contain lysosomal enzymes bound to mannose 6-phosphate receptors. 613 57

The covalent attachment of polyethylene glycol (PEG) to beta-glucosidase from sweet almonds and alpha-galactosidase from green coffee beans results in alterations of their catalytic properties and masking of specific determinant sites on the enzymes. Both enzymes have increased Km and decreased Vmax values against their respective p-nitrophenyl substrate analogs after PEG attachment. When PEG is attached to 30% of alpha-galactosidase epsilon-amino groups, 12% activity remains against ceramide trihexoside, while its ability to convert type B erythrocytes to type H specificity is lost. However, it still is able to cleave terminal galactose residues from human saliva blood group substance B. PEG-beta-glucosidase (38%) did not elicit the production of complement-fixing antibodies, nor did it react with antibodies produced against the native enzyme. Antibody and lectin-specific binding were lost from both modified enzymes (PEG-beta-glucosidase and PEG-alpha-galactosidase). After conjugation with PEG, beta-glucosidase lost its ability to bind to concanavalin A-Sepharose. Antibodies directed against native alpha-galactosidase blocked its enzyme activity, but lost their ability to inhibit activity in progressively higher modified preparations of the enzyme. Antisera against PEG-alpha-galactosidase (53%) did not inhibit enzyme activity in any alpha-galactosidase or PEG-alpha-galactosidase preparation. These results indicate that PEG tends to cover lectin-specific carbohydrate moieties and antigenic determinants and that these sites probably remain cryptic during in vivo processing of PEG-enzymes.
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PMID:Enzyme therapy: II. Effect of covalent attachment of polyethylene glycol on biochemical parameters and immunological determinants of beta-glucosidase and alpha-galactosidase. 620 60

Escherichia coli K12 does not metabolize beta-glucosides such as arbutin and salicin because of lack of expression of the bglBSRC operon, which contains structural genes for transport (bglC) and hydrolysis (bglB) of phospho-beta-glucosides. Mutants carrying lesions in the cis-acting regulatory site bglR metabolize beta-glucosides as a consequence of expression of this cryptic operon (Prasad and Schaefler 1974). We isolated mutations promoting beta-glucoside metabolism that were unlinked to bglR; some of these mutations were shown to be amber. All of them were mapped at 27 min on the E. coli K12 linkage map and appeared to define a single gene, for which we propose the designation bglY. Utilization of beta-glucosides in bglY mutants appeared to be a consequence of expression of the bglBSRC operon, since bglB bglR and bglB bglY double mutants had the same phenotype. All bglY mutations analyzed were recessive to the wild-type bglY+ allele. Phospho-beta-glucosidase B and beta-glucoside transport activities are inducible in bglY mutants, as they are in bglR mutants. Metabolism of beta-glucosides in both bglR and bglY mutants required cyclic AMP. We propose that bglY encodes a protein acting as a repressor of the bglBSRC operon, active in both the presence and absence of beta-glucosides, whose recognition site would be within the bglR locus.
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PMID:Cryptic operon for beta-glucoside metabolism in Escherichia coli K12: genetic evidence for a regulatory protein. 626 10

A strain of bakers' yeast was isolated which could utilize cellobiose and other beta-D-glucosides quantitatively as carbon and energy sources for growth. Cellobiose-grown cells contained a largely cryptic enzyme active against the chromogenic substrate p-nitrophenyl-beta-D-glucoside. The patent (intact cell) activity of such cells was inhibited by azide and, competitively, by cellobiose; neither agent inhibited the beta-glucosidase activity of lysed cells or of extracts. The enzyme induced by growth in cellobiose medium had no affinity for cellobiose as either substrate or inhibitor; its substrate specificity classifies it as an aryl-beta-glucosidase. It was concluded that growth in cellobiose also induced the formation of a stereospecific and energy-dependent system whose function determined the rate at which intact cells could hydrolyze substrates of the intracellular beta-glucosidase.
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PMID:AN INDUCIBLE SYSTEM FOR THE HYDROLYSIS AND TRANSPORT OF BETA-GLUCOSIDES IN YEAST. I. CHARACTERISTICS OF THE BETA-GLUCOSIDASE ACTIVITY OF INTACT AND OF LYSED CELLS. 1432 93

Escherichia coli strains, in general, do not ferment cellobiose and aryl-beta-D-glucosidic sugars, although "cryptic" beta-d-glucoside systems have been characterized. Here we describe an additional cryptic operon (bgc) for the utilization of cellobiose and the aryl-beta-d-glucosides arbutin and salicin at low temperature. The bgc operon was identified by the characterization of beta-glucoside-positive mutants of an E. coli septicemia strain (i484) in which the well-studied bgl (aryl-beta-d-glucoside) operon was deleted. These bgc* mutants appeared after 5 days of incubation on salicin indicator plates at 28 degrees C. The bgc operon codes for proteins homologous to beta-glucoside/cellobiose-specific phosphoenolpyruvate-dependent phosphotransfer system permease subunits IIB (BgcE), IIC (BgcF), and IIA (BgcI); a porin (BgcH); and a phospho-beta-D-glucosidase (BgcA). Next to the bgc operon maps the divergent bgcR gene, which encodes a GntR-type transcriptional regulator. Expression of the bgc operon is dependent on the cyclic-AMP-dependent regulator protein CRP and positively controlled by BgcR. In the bgc* mutants, a single nucleotide exchange enhances the activity of the bgc promoter, rendering it BgcR independent. Typing of a representative collection of E. coli demonstrated the prevalence of bgc in strains of phylogenetic group B2, representing mainly extraintestinal pathogens, while it is rare among commensal E. coli strains. The bgc locus is also present in the closely related species Escherichia albertii. Further, bioinformatic analyses demonstrated that homologs of the bgc genes exist in the enterobacterial Klebsiella, Enterobacter, and Citrobacter spp. and also in gram-positive bacteria, indicative of horizontal gene transfer events.
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PMID:Characterization of a beta-glucoside operon (bgc) prevalent in septicemic and uropathogenic Escherichia coli strains. 1923 52