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)

Cellobiase has been isolated from the crude cellulase mixture of enzymes of Trichoderma viride using column chromatographic and ion-exchange methods. The steady-state kinetics of the hydrolysis of cellobiose have been investigated as a function of cellobiose and glucose concentrations, pH of the solution, temperature, and dielectric constant, using isopropanol-buffer mixtures. The results show that (i) there is a marked activation of the reaction by initial glucose concentrations of 4 X 10(-3) M to 9 X 10(-2) M and strong inhibition of the reaction at higher initial concentrations, (ii) the log rate -pH curve has a maximum at pH 5.2 and enzyme pK values of 3.5 and 6.8, (iii) the energy of activation at pH 5.1 is 10.2 kcal mol-1 over the temperature range 5-56 degrees C, and (iv) the rate decreases from 0 to 20% (v/v) isopropanol. The hydrolysis by cellobiase (EC 3.2.1.21) of p-nitrophenyl-beta-D-glucoside was examined by pre-steady-state methods in which [enzyme]0 greater than [substrate]0, and by steady-state methods as a function of pH and temperature. The results show (i) a value for k2 of 21 S-1 at pH 7.0 (where k2 is the rate constant for the second step in the assumed two-intermediate mechanism (formula: see text), (ii) a log rate -pH curve, significantly different from that for hydrolysis of cellobiose, in which the rate increases with decreasing pH below pH 4.5, is constant in the region pH 4.5-6, and decreases above pH 6 (exhibiting an enzyme pK value of 7.3), and (iii) an activation energy of 12.5 kcal mol-1 at pH 5.7 over the temperature range 10-60 degrees C.
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PMID:Kinetics of the hydrolysis of cellobiose and p-nitrophenyl-beta-D-glucoside by cellobiase of Trichoderma viride. 1 17

Stability of C1- and C2-cellulases, CX-exo- and CX-endoglucanases and beta-glucosidase of Aspergillus awamori was studied as affected by monoatomic aliphatic alcohols --methanol, ethanol, propanol and isopropanol; bi- and triatomic alcohols - ethylene glycol and glycerol, urea as well as detergents of dodecyl sulphate and sodium nonilate. The mentioned enzymes are established to manifest the highest activity in 40-60% glycerol. It is also shown that their stability is changed differently under the effect of other alcohols, urea and detergents. The latter testifies to the fact that the studied enzymes are nonidentical, in particular, they differ between themselves by a ratio of intramolecular forces which stabilize their macrostructure.
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PMID:[Role of intramolecular bonds in stability of certain enzymes of the cellulolytic complex]. 125 59

An intracellular beta-glucosidase was isolated from the cellobiose-fermenting yeast, Candida wickerhamii. Production of the enzyme was stimulated under aerobic growth, with the highest level of production in a medium containing cellobiose as a carbohydrate source. The molecular mass of the purified protein was approximately 94 KDa. It appeared to exist as a dimeric structure with a native molecular mass of about 180 KDa. The optimal pH ranged from 6.0 to 6.5 with p-nitrophenyl beta-D-glucopyranoside (NpGlc) as a substrate. The optimal temperature for short-term (15-min) assays was 35 degrees C, while temperature-stability analysis revealed that the enzyme was labile at temperatures of 28 degrees C and above. Using NpGlc as a substrate, the enzyme was estimated to have a Km of 0.28 mM and a Vmax of 525 mumol product min-1 mg protein-1. Similar to the extracellular beta-glucosidase produced by C. wickerhamii, this enzyme resisted end-product inhibition by glucose, retaining 58% of its activity at 100 mM glucose. The activity of the enzyme was highest against aryl beta-1,4-glucosides. However, p-nitrophenyl xylopyranoside, lactose, cellobiose, and trehalose also served as substrates for the purified protein. Activity of the enzyme was stimulated by long-chain n-alkanols and inhibited by ethanol, 2-propanol, and 2-butanol. The amino acid sequence, obtained by Edman degradation analysis, suggests that this beta-glucosidase is related to the family-3 glycosyl hydrolases.
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PMID:Properties of an intracellular beta-glucosidase purified from the cellobiose-fermenting yeast Candida wickerhamii. 898 23

An extracellular beta-glucosidase from Thermoascus aurantiacus was purified to homogeneity by DEAE-Sepharose, Ultrogel AcA 44 and Mono-P column chromatography. The enzyme was a homotrimer, with a monomer molecular mass of 120 kDa; only the trimer was optimally active at 80 degrees C and at pH 4.5. At 90 degrees C, the enzyme showed 70% of its optimal activity. It was stable at pH 5.2 and at temperatures up to 70 degrees C for 48 h, but stability decreased above 70 degrees C and at pH values above and below 5.0. The enzyme hydrolysed aryl and alkyl beta-d-glucosides and cello-oligosaccharides, and was specific for substrates with a beta-glycosidic linkage. The hydroxy groups at positions 2, 4 and 6 of a glucose residue at the non-reducing end of a disaccharide appeared to be essential for catalysis. The enzyme had the lowest K(m) towards p-nitrophenyl beta-d-glucoside (0.1137 mM) and the highest k(cat) towards cellobiose and beta,beta-trehalose (17052 min(-1)). It released one glucose unit at a time from the non-reducing end of cello-oligosaccharides, and the rate of hydrolysis decreased with an increase in chain length. Glucose and d-delta-gluconolactone inhibited the beta-glucosidase competitively, with K(i) values of 0.29 mM and 8.3 nM respectively, while methanol, ethanol and propan-2-ol activated the enzyme. The enzyme catalysed the synthesis of methyl, ethyl and propyl beta-d-glucosides in the presence of methanol, ethanol and propan-2-ol respectively with either glucose or cellobiose, although cellobiose was preferred. An acidic pH favoured hydrolysis and transglycosylation, but high concentrations of alcohols favoured the latter reaction. The stereochemistry of cellobiose hydrolysis revealed that beta-glucosidase from T. aurantiacus is a retaining glycosidase, while N-terminal amino acid sequence alignment indicated that it is a member of glycoside hydrolase family 3.
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PMID:Biochemical characterization and mechanism of action of a thermostable beta-glucosidase purified from Thermoascus aurantiacus. 1111 5

Enzymatic glycosidation of twenty-one kinds of alcohols (n-hepanol, n-octanol, 2-phenylethanol, 3-phenylpropanol, 4-phenylbutanol, 5-phenylpentanol, 6-phenylhexanol, furfury alcohol, 2-pyridinemethanol, isobutanol, isopentanol, p-methoxycinnamylalcohol) including secondary alcohols (isopropanol, cyclohexanol, 1-phenylethanol) and 1,omega-alkanediols (1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol), salicyl alcohol and 4-nitrophenyl beta-D-glucopyranoside (5) using beta-glucosidase from almonds stereoselectively gave the corresponding beta-D-glucopyranosides in moderate yield.
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PMID:Simple synthesis of beta-D-glycopyranosides using beta-glycosidase from almonds. 1475 17

The biosynthetic activity of yeast Pichia etchellsii beta-glucosidase II (BglII) expressed in recombinant Escherichia coli was utilized for synthesis of cellooligosaccharides, alkyl and terpene glucosides. Cellooligosaccharides with a degree of polymerization of 3 and greater were resolved by thin-layer chromatography (TLC) using an ethyl acetate:1-propanol:2-propanol:water (8:5:1:1) solvent system followed by visualization with 0.2% naphthoresorcinol reagent. Using 2M cellobiose and 15 IU of partially purified BglII, 57 mmol/L of oligosaccharides (comprising mostly cellotriose and cellopentaose) was synthesized in 16 h. Similarly, alkyl glucosides with chain lengths from 6 to 10 carbons were synthesized and products extracted to near purity by ethyl acetate extraction. The same extraction method was employed to separate, to near purity, various monoterpenyl (nerol, geraniol, citronellol) glucosides. A reliable and simple method for separation of cellooligosaccharides using a combination of Bio-Gel P-2 gel filtration and charcoal celite adsorption chromatography was developed. The cellooligosaccharides were separated to purity as confirmed by TLC. The enzyme was among the very few that could synthesize a wide variety of glycoconjugates.
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PMID:Enzymatic synthesis of oligosaccharides, alkyl and terpenyl glucosides, by recombinant Escherichia coli-expressed Pichia etchellsii beta-glucosidase II. 1530 55

The properties of two isozymes of beta-glucosidase of Penicillium funiculosum (part I of this series) are described. The molecular weights of isozyme 1 was 2.3 x 10(5) by gel filtration and 1.2 x 10(5) by SDS gel electrophoresis, indicating two subunits. The molecular weight of isozyme 2 was unusually low for a fungal beta-glucosidase: 1.6 x 10(4) by gel filtration and 3.7 x 10(4) in the presence of isopropanol. The two enzymes differed from other fungal beta-glucosidases in their substrate specificities. They showed high activity with pNPG, cellobiose, cellotriose, cellotetraose, cellopentaose, gentiobiose, and laminarin, but were inactive with filter paper, CM cellulose, or derivatives or stabilized by bovine serum albumin and several alcohols such as butanol and propanol. It was inhibited by glucono-delta-lactone (K(i) = 0.67muM) and glucose (K(i) = 0.92mM).The enzyme was quantitatively adsorbed by P. funiculosum mycelium at pH 4 and the immobilized enzyme was as enzymically active as the free enzyme, but more heat stable. The binding efficiency was very high (5000 IU enzyme/g mycelium). It could be quantitatively eluted with buffers at pH 7 or by 0.02M Ca, Mg, or Al chlorides. The binding was selective, since mycelium grown on lactose could produce and also bind only beta-glucosidase isozyme 1, whereas mycelium grown on cellulose could produce as well as bind both beta-glucosidase isozymes as well as cellulases. Mycelial binding was unaffected by washing with EDTA or trypsinization, but was totally lost by washing with dilute KOH, HCl, or ethylenediamine.
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PMID:beta-Glucosidase of Penicillium funiculosum. II. Properties and mycelial binding. 1855 37

Synthetic microbial consortia consisting of microorganisms with different synthetic genetic circuits or divided synthetic metabolic pathway components can exert functions that are beyond the capacities of single microorganisms. However, few consortia of microorganisms with different synthetic genetic circuits have been developed. We designed and constructed a synthetic microbial consortium composed of an enzyme-producing strain and a target chemical-producing strain using Escherichia coli for chemical production with efficient saccharification. The enzyme-producing strain harbored a synthetic genetic circuit to produce beta-glucosidase, which converts cellobiose to glucose, destroys itself via the lytic genes, and release the enzyme when the desired cell density is reached. The target chemical-producing strain was programmed by a synthetic genetic circuit to express enzymes in the synthetic metabolic pathway for isopropanol production when the enzyme-producing strain grows until release of the enzyme. Our results demonstrate the benefits of synthetic microbial consortia with distributed tasks for effective chemical production from biomass.
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PMID:Synthetic microbial consortium with specific roles designated by genetic circuits for cooperative chemical production. 3140 Dec 44

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