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)

Differential gene expression at the transcriptional level was examined as an initial step in the investigation of the P(i) starvation response of Brassica nigra suspension cells. Total RNA was extracted from 7-day old cells grown in media containing either no P(i), 1.25 mM or 10 mM Pi. In vitro translation was carried out using their respective poly(A)+ RNA isolates and the resultant polypeptides were separated on a high-resolution SDS-PAGE gel. Scanning densitometry identified four polypeptides (ca. 31.7, 32.3, 52.5 and 64.8 kDa) present only in the P(i)-starved samples. Screening by differential hybridization was performed on a cDNA library constructed from mRNA isolated from P(i)-starved cells. Probes prepared from mRNA from P(i)-deficient and P(i)-sufficient cells identified a number of clones representing mRNA species that were preferentially transcribed under P(i) deficiency. These phosphate starvation-responsive (psr) clones were placed into eleven groups as determined by cross-hybridization. Northern blots showed that the corresponding genes are inducible in both mild and severe P(i) starvation conditions. Preliminary sequencing identified one of the clones as being homologous to beta-glucosidases from several plant species. The possible role of beta-glucosidase during Pi starvation and the identities of the other psr genes are discussed.
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PMID:Isolation of cDNA clones of genes with altered expression levels in phosphate-starved Brassica nigra suspension cells. 764 Mar 58

An inducible intracellular beta-glucosidase (EC 3.2.1.21) from Streptomyces sp. QM-B814 (ATCC 11238) has been purified and characterized. The purified polypeptide is monomeric with a relative molecular mass of 62 kDa by SDS-PAGE and 42 kDa by size-exclusion chromatography; its isoelectric point is 4.2. The difference in the molecular mass values can be attributed to the glycosylated nature of the protein. The purified enzyme has a pH optimum of 6.0-6.5. The temperature optimum for activity is 50 degrees C; at this temperature the enzyme is stable for 1 h. The enzyme hydrolyzes mainly aryl-beta-glucosides but also presents significant activity against beta-linked disaccharides and maltose. The enzyme displays an unusual kinetic behavior and biphasic Lineweaver-Burk and Eadie-Hofstee plots for p-nitrophenyl-beta-D-glucoside and cellobiose were obtained. The enzyme presents beta-glycosyltransferase activity and an exoglycosidase-type action on cellodextrins. It is inhibited by delta-gluconolactone (Ki 0.44 mM) but, remarkably, glucose in the range 25-200 mM enhances the rate of p-nitrophenyl-beta-D-glucoside hydrolysis.
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PMID:Properties of a novel glucose-enhanced beta-glucosidase purified from Streptomyces sp. (ATCC 11238). 766 3

A yeast strain isolated in the laboratory from fermenting agave (Agave sp.) juice was studied and classified as Candida entomophila. The beta-glucosidase of this yeast was purified by ion-exchange chromatography and gel filtration. Its molecular mass estimated by gel filtration was 400 kDa. The oligomeric structure was determined following treatment of the purified enzyme with SDS. Its optimum pH was between 5 and 6, and its optimum temperature was 60 degrees C. The enzyme was active against soluble glucosides with (1-->3)-beta, (1-->4)-beta and (1-->4)-alpha linkage configuration, and it possesses (1-->6)-alpha-arabinofuranosidase activity. It is competitively inhibited by glucose and by D-gluconic acid lactone. The enzyme was constitutive and a glucosyltransferase activity is observed in the presence of ethanol. Since the glycosides present in wines and fruit juices represent a potential source of aromatic flavour, the possible use of the yeast glucosidase for the liberation of the bound aroma is discussed.
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PMID:Purification and characterization of the endocellular beta-glucosidase of a new strain of Candida entomophila isolated from fermenting agave (Agave sp.) juice. 798 78

Phanerochaete chrysosporium is the best studied organism with respect to lignin degradation, but its degradation of the xylan component of lignocellulose is only now being studied. When grown on oat spelt xylan (mainly arabinoxylan), it produces an enzyme with beta-D-xylosidase and beta-D-glucosidase activity. This enzyme was purified by ultrafiltration followed by ammonium sulphate precipitation, anion-exchange chromatography using DEAE Biogel and Mono Q, and gel filtration using Superose 12. It is extracellular, with an apparent M(r) value of 44,500 as determined by SDS-PAGE; the pI is 4.67 and activity is maximal at pH 5 and 60 degrees C. The enzyme is of particular interest because its principal activity is against laminaribiose (3-O-beta-D-glucopyranosyl-D-glucopyranose and laminarin [(1-->3)-beta-D-glucan with ca. 3% of beta-(1-->6) branches] rather than cellobiose and xylobiose. It was competitively inhibited by D-glucono-1,5-lactone and deoxynojirimycin; with p-nitrophenyl beta-D-xylopyranoside as substrate, the Ki values were 32 and 87.5 microM, respectively, and with p-nitrophenyl beta-D-glucopyranoside, they were 35 and 68.7 microM, respectively. The Km values with p-nitrophenyl beta-D-xylopyranoside and p-nitrophenyl beta-D-glucopyranoside as substrates were 3.51 and 5.30 mM, respectively.
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PMID:A Phanerochaete chrysosporium beta-D-glucosidase/beta-D-xylosidase with specificity for (1-->3)-beta-D-glucan linkages. 815 53

A beta-D-glucosidase and a beta-D-xylosidase were purified to homogeneity from the thermophilic eubacterium Thermotoga sp. strain FjSS3-B.1. Both enzymes were largely cell-associated and were probably associated with the 'toga' structures of this organism. Using SDS-PAGE they were found to have M(r) values of 75,000 and 92,000, respectively. The beta-glucosidase was active against cellobiose, sophorose and gentiobiose with Km values of 59 mM, 2.7 mM and 6 mM, respectively. The beta-xylosidase had a Km of 2 mM for xylobiose, showed strong activity against p-nitrophenyl alpha-L-arabinofuranoside and p-nitrophenyl alpha-L-arabinopyranoside, but was subject to strong substrate inhibition by p-nitrophenyl beta-D-xylopyranoside. Both enzymes were extremely thermostable, with half-lives of several hours at 98 degrees C. The thermostabilities of both enzymes were increased further by the addition of either trehalose or betaine.
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PMID:Thermostable beta-glucosidase and beta-xylosidase from Thermotoga sp. strain FjSS3-B.1. 842 76

The 450 kDa cellobiase from Termitomyces clypeatus which migrates as a single band on IEF, PAGE and SDS-PAGE, was found to possess appreciable sucrase activity. The fungus produced sucrase and cellobiase constitutively in different media but with different activity ratios. The kinetics of secretion of the two enzymes was similar under in vivo and in vitro conditions. HPGPLC analysis of the culture filtrates indicated the presence of both sucrase and cellobiase in the same protein fractions of different molar mass, even in the 30-kDa protein fraction. No free sucrase or cellobiase could be detected in the culture filtrates. It was also observed that fractionation of cellobiase by (NH4)2SO4 precipitation was different with different amounts of associated sucrase activity present in the culture filtrate. The (NH4)2SO4-precipitated cellobiase fraction also contained cellobiases in proteins of widely varied molar mass ranges. However, none of the low-molar mass proteins other than the 450-kDa enzyme could be purified, as all low-molar-mass fractions spontaneously aggregated to the 450-kDa enzyme. Hydrophobic chromatography of the (NH4)2SO4-precipitated fractions followed by HPGPLC of the eluted active fraction yielded both cellobiase-free sucrase and a very low sucrase-containing cellobiase fraction. The cellobiase fraction, homogeneous in PAGE, was also a high-molar-mass protein complex dissociating into a number of protein bands on SDS-PAGE.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Development of high-molar-mass cellobiase complex by spontaneous protein-protein interaction in the culture filtrate of Termitomyces clypeatus. 854 93

The thermophilic fungus Humicola grisea var. thermoidea produced beta-glucosidase activity when grown in a solid-state culture on wheat bran as carbon source. A beta-glucosidase was purified to apparent homogeneity by ultrafiltration, gel filtration chromatography on Sephacryl S-100, and ion-exchange chromatography on S-Sepharose, as judged by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) on a 12.5% (w/v) slab gel. The enzyme had a molecular mass of 82 and 156 kDa, as estimated by SDS-PAGE and gel filtration on a high performance liquid chromatographic column, respectively, suggesting that the native enzyme may consist of two identical subunits. The purified enzyme was thermostable at 60 degrees C for 1 h with a half-life of 15 min at 65 degrees C, and displayed optimum activity at 60 degrees C and a pH range. of 4.0-4.5. The Km and Vmax values for p-nitrophenyl beta-D-glucopyranoside were determined to be 0.316 mM and 0.459 IU.mL-1, respectively. D-Glucose, D-gluconic acid lactone, Hg2+, Cu2+, and Mn2+ inhibited beta-glucosidase activity. The enzyme activity was competitively inhibited by D-glucose (ki = 0.6 mM). The purified enzyme was very active against cellobiose and p-nitrophenyl beta-D-glucopyranoside.
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PMID:Purification and characterization of a beta-glucosidase from solid-state cultures of Humicola grisea var. thermoidea. 859 91

Xylaria regalis, a wood-grown ascomycete isolated in Taiwan, produces beta-glucosidase (EC 3.2.1.21) extracellularly. The beta-glucosidase was purified to homogeneity by ammonium sulfate precipitation, ion-exchange, and gel filtration chromatography. The molecular mass of the purified enzyme was estimated to be 85 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. With p-nitrophenyl beta-D-glucopyranoside (PNPG) as the substrate at pH 5.0 and 50°C, the Km was 1.72 mM and Vmax was 326 &mgr;mol/min/mg. Optimal activity with PNPG as the substrate was at pH 5.0 and 50°C. The enzyme was stable at pH 5.0 at temperatures up to 50°C. The purified beta-glucosidase was active against PNPG, cellobiose, sophorose, and gentiobiose, but did not hydrolyze lactose, sucrose, Avicel, and o-nitrophenyl beta-D-galactopyranoside. The activity of beta-glucosidase was stimulated by Ca2+, Mg2+, Mn2+, Cd2+ and beta-mercaptoethanol, and inhibited by Ag+, Hg2+, SDS, and p-chloromercuribenzoate (PCMB).
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PMID:Purification and Characterization of an Extracellular beta-Glucosidase from the Wood-Grown Fungus Xylaria regalis 887 9

The anaerobic fungus Neocallimastix sp. strain L2,isolated from the feces of a llama, was tested for growth on a range ofsoluble and insoluble carbohydrate substrates. The fungus was able to fermentglucose, cellobiose, fructose, lactose, maltose, sucrose, soluble starch,inulin, filter paper cellulose, and Avicel. No growth was observed onarabinose, galactose, mannose, ribose, xylose, sorbitol, pectin, xylan,glycerol, citrate, soya, and wheat bran. The fermentation products aftergrowth were hydrogen, formate, acetate, ethanol, and lactate. Thefermentation pattern was dependent on the carbon source. In general, higherhydrogen production resulted in decreased formation of lactate and ethanol.Recovery of the fermented carbon in products at the end of growth ranged from50% to 80%. (Hemi)cellulolytic enzyme activities were affectedby the carbon source. Highest activities were found in filtrates fromcultures grown on cellulose. Growing the fungus on inulin and lactose yieldedthe lowest cellulolytic activities. Highest specific activities foravicelase, endoglucanase, beta-glucosidase, and xylanase were obtained withAvicel as the substrate for growth (0.29, 5.9, 0.57, and 13IU · mg-1 protein, respectively). Endoglucanase activitybanding patterns after SDS-PAGE were very similar for all substrates. Minordifferences indicated that enzyme activities may in part be the result ofsecretion of different sets of isoenzymes.
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PMID:The Anaerobic Fungus Neocallimastix sp. Strain L2: Growthand Production of (Hemi)Cellulolytic Enzymes on a Range of CarbohydrateSubstrates 900 85

A beta-D-glucanase activity hydrolyzing 1,3:1,4-beta-D-glucan was released from the cell walls of barley by 3 M LiCl treatment. It was purified by sequential cation-exchange, gel-filtration and hydrophobic chromatography. The molecular mass of the glucanase was 66 kDa as determined by SDS-polyacrylamide gel electrophoresis. Sequence determination of the first thirty amino acids of the N-terminus revealed a high homology of this enzyme to the Pseudomonas 1,4-beta-D-glucosidase (56.5%). The purified beta-D-glucanase has a pH optimum at 5.0, and hydrolyzes oligosaccharides containing beta-D-1,3 or beta-D-1,4 linkage. The glucanase showed maximum hydrolytic activity toward laminaritetraose, the rate being about two times that of cellotetraose and about four times that of gentiobiose. Polysaccharides such as lichenan, 1,3:1,4-beta-D-glucan (from barley), laminarin and pustulan are also hydrolyzed, but not carboxylmethyl-curdlan, carboxymethyl-cellulose, xyloglucan and maltose. The purified beta-D-glucanase yielded monomeric glucose from laminarihexaose, and exhibited characteristics of an exo-1,3-beta-D-glucanase (EC 3.2.1.58). The activity and biochemical characteristics of this enzyme suggest that it is an exo-1,3-beta-D-glucanase involved in the rapid turnover of 1,3:1,4-beta-D-glucan in barley cell walls during seedling growth.
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PMID:Purification and characterization of wall-bound exo-1,3-beta-D-glucanase from barley (Hordeum vulgare L.) seedlings. 909 82


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