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)

A cellobiohydrolase I (cbhI) and a beta-glucosidase 1 (bgl1) gene of Aspergillus aculeatus were expressed in Saccharomyces cerevisiae. The transformed cells secreted the enzymes efficiently in an active form. The recombinant CBHI gave two bands of different molecular mass (110 and 90 kDa) and the recombinant BGL1 gave one band (180 kDa) by SDS-PAGE. The recombinant CBHI and BGL1 had the same enzymatical properties as the native enzyme except for the specific activity toward cellulosic substrates. By the combination of three different types of cellulases, FI-CMCase, CBHI, and BGL1, we could hydrolyze Avicel up to 59% under our experimental conditions.
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PMID:Expression of Aspergillus aculeatus No. F-50 cellobiohydrolase I (cbhI) and beta-glucosidase 1 (bgl1) genes by Saccharomyces cerevisiae. 975 70

Plant cell suspension cultures of Rauwolfia produce within 1 week approximately 250 nkat/l of raucaffricine-O-beta-D-glucosidase. A five step procedure using anion exchange chromatography, chromatography on hydroxylapatite, gel filtration and FPLC-chromatography on Mono Q and Mono P delivered in a yield of 0.9% approximately 1200-fold enriched glucosidase. A short protocol employing DEAE sepharose, TSK 55 S gel chromatography and purification on Mono Q gave a 5% recovery of glucosidase which was 340-fold enriched. SDS-PAGE showed a Mr for the enzyme of 61 kDa. The enzyme is not glycosylated. Structural investigation of the enzyme product, vomilenine, demonstrated that the alkaloid exists in aqueous solutions in an equilibrium of 21(R)- and 21(S)-vomilenine in a ratio of 3.4:1. Proteolysis of the pure enzyme with endoproteinase Lys C revealed six peptide fragments with 6-24 amino acids which were sequenced. The two largest fragments showed sequences, of which the motif Val-Thr-Glu-Asn-Gly is typical for beta-glucosidases. Sequence alignment of these fragments demonstrated high homologies to linamarase from Manihot esculenta (81% identity) or to beta-glucosidase from Prunus avium (79% identity). Raucaffricine-O-beta-D-glucosidase seems to be a new member of the family 1 of glycosyl hydrolases.
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PMID:Purification, partial amino acid sequence and structure of the product of raucaffricine-O-beta-D-glucosidase from plant cell cultures of Rauwolfia serpentina. 1023 58

Three cellobiases, here called cellobiase A, B, and C, from the culture filtrate of Aspergillus niger A20, were purified by precipitation with ammonium sulphate, gel filtration through Sephadex G-75, and column chromatography of DEAE-cellulose. The purified enzymes were homogeneous on polyacrylamide disk electrophoresis. The mol wt of the purified enzymes were estimated by SDS-gel electrophoresis to be 88,000, 80,000, and 71,000 for cellobiases A, B, and C, respectively. The enzymes were active at pH 4.5 and 55-60 degrees C. The pattern of their amino acid compositions showed high contents of aspartic acid, glutamic acid, threonine, serine, and glycine. The apparent K(m) values for cellobiose were 0.9, 1.63, and 1.0 mM for cellobiases A, B, and C, respectively. Calcium ions stimulated cellobiases B and C, and Co2+ and Mg2+ ions stimulated cellobiase A. The purified enzymes hydrolyzed cellobiose and aryl-beta-D-glucosides, but they had no action on sucrose, maltose, and cellulose. The three cellobiases catalyzed transglycosylase reaction, and the major product formed from cellobiose was tetramer of glucose.
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PMID:Purification and properties of three cellobiases from Aspergillus niger A20. 1032 88

Myrosinase (thioglucoside glucohydrolase; EC 3.2.3.1) is a plant enzyme that hydrolyses glucosinolates, principally to isothiocyanates. Myrosinase was purified to homogeneity in good yield from 8-day-old seedlings of Raphanus sativus (daikon) using a four-step procedure involving chromatographies on anion exchange, hydrophobic Phenyl-Sepharose, gel filtration and concanavalin A-Sepharose. In order to stabilize the enzyme and to avoid excessive peak broadening during chromatography, 30% (v/v) glycerol was added to dialysis and chromatography buffers. The purified enzyme was eluted as a single peak from a gel-filtration sizing column with an apparent molecular mass of 120 kDa. The enzyme was resolved into two subunits with molecular masses of 61 and 62 kDa by SDS/PAGE. Ascorbic acid activated the purified enzyme more than 100-fold. The V(max) and K(m) values for the hydrolysis of allyl glucosinolate (sinigrin) were 2.06 micromol/min per mg of protein and 23 microM in the absence of ascorbate and 280 micromol/min per mg of protein and 250 microM in the presence of 500 microM ascorbate, respectively. As the ascorbate concentration was increased from 50 to 500 microM, the V(max) and K(m) values increased in parallel, and thus the V(max)/K(m) ratio remained constant. Similarly, raising the concentrations of sinigrin increased the concentration of ascorbic acid required for half-maximal activation (K(a)). At a sinigrin concentration of 250 microM, the K(a) for ascorbic acid was 55 microM. Sulphate, a reaction product, was a competitive inhibitor of activity, having a K(i) of 60 mM with respect to sinigrin and of 27 mM with respect to ascorbate. Thus activation of myrosinase from R. sativus by ascorbic acid exemplifies an unusual and possibly unique example of linear 'uncompetitive activation' (i.e. a proportionate increase in V(max) and K(m)) of an enzyme. The enzyme also had beta-glucosidase activity and hydrolysed p-nitrophenyl-beta-d-glucopyranoside.
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PMID:An unusual case of 'uncompetitive activation' by ascorbic acid: purification and kinetic properties of a myrosinase from Raphanus sativus seedlings. 1041 37

An extracellular xylanase was purified to homogeneity from the culture filtrate of a thermophilic fungus, Thermomyces lanuginosus-SSBP, and its biochemical characteristics were studied. A yield of 70-80% was achieved through the procedures of 80%-satd. ammonium sulphate precipitation, DEAE-Sephadex A25 and quaternary aminoethyl (QAE)-Sephadex A25 column chromatography. The molecular mass of the purified xylanase was 23.6 kDa, as analysed by SDS/PAGE, with a pI value of 3.8. The molar absorption coefficient of the absorbance at 280 nm was 6.8x10(4) M(-1).cm(-1). The specific activity, calculated using the dinitrosalicylic acid (DNS) method, was 3500 units/mg. The enzyme reactions followed Michaelis-Menten kinetics with K app m and V(max) values of 3.26 mg/ml and 6300 units/ml per mg of protein respectively, as obtained from a Lineweaver-Burk plot. The xylanase contained no other enzyme activity (cellulase, beta-glucosidase, beta-mannosidase, alpha-arabinofuranosidase, or beta-xylosidase) except for the hydrolysis of xylan substrate. The optimal temperature of the enzyme assay was 70-75 degrees C. The enzyme retained full activity after a 60 degrees C incubation for 3 h. The optimal pH of xylanase activity was 6.5 and the enzyme appeared to be stable over a broad pH range (pH 5-12) under the assay conditions. The majority of the metal ions tested had no effect on the enzyme activity, with the exception of Pb(2+) (modest inhibitor) and Hg(2+) (strong inhibitor). The results showed that one or two tryptophan residues oxidized by N-bromosuccinamide per enzyme molecule was sufficient to inhibit the enzyme activity completely, thus indicating that the tryptophan residues play an important role in the catalytical processes of the enzyme reaction. Because of the outstanding properties of the purified xylanase from the SSBP strain, this xylanase has a potential use in biopulping processes and other industrial applications.
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PMID:Purification and biochemical characteristics of beta-D-xylanase from a thermophilic fungus, Thermomyces lanuginosus-SSBP. 1046 22

An extracellular beta-glucosidase II (beta-Glu II) has been purified to homogeneity by column chromatography from Aspergillus niger CCRC 31494. Its molecular mass was estimated to be 360 kDa by gel filtration and 120 kDa by SDS-PAGE. The enzyme has a pI of 4.0 and has optimum activity at pH 4.5 and 60 degrees C. The beta-Glu II was completely inhibited by 5.0 mM Fe(2+). Methanol (20%, v/v) activated the enzyme activity at 1.8-fold. V(max) values of 10.2 and 464 units/mg were found for p-nitrophenyl beta-D-glucoside (K(m) = 2.2 mM) and for cellobiose (K(m) = 15.4 mM). The enzyme was strongly inhibited by substrates, p-nitrophenyl beta-D-glucopyranoside in excess of 7.5 mM and cellobiose in excess of 50 mM, and was competitively inhibited by glucose with a K(i) of 5.7 mM. Transglucosylation products of cellotriose, methyl beta-glucoside and ethyl beta-glucoside, were obtained under neutral conditions and in the presence of methanol and ethanol, respectively.
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PMID:Purification and Characterization of an Extracellular beta-Glucosidase II with High Hydrolysis and Transglucosylation Activities from Aspergillus niger. 1055 58

An alpha-L-rhamnosidase clone was isolated from a genomic library of the thermophilic anaerobic bacterium Clostridium stercorarium and its primary structure was determined. The recombinant gene product, RamA, was expressed in Escherichia coli, purified to homogeneity and characterized. It is a dimer of two identical subunits with a monomeric molecular mass of 95 kDa in SDS polyacrylamide gel electrophoresis. At pH 7.5 it is optimally active at 60 degrees C and insensitive to moderate concentrations of Triton X100, ethanol and EDTA. It hydrolysed p-nitrophenyl-alpha-L-rhamnopyranoside, naringin and hesperidin with a specific activity of 82, 1.5 and 0.46 U mg-1 respectively. Hydrolysis occurs by inversion of the anomeric configuration as detected using 1H-NMR, indicating a single displacement mechanism. Naringin was hydrolysed to rhamnose and prunin, which could further be degraded by incubation with a thermostable beta-glucosidase. The secondary structure of RamA consists of 27% alpha-helices and 50% beta-sheets, as detected by circular dichroism. The primary structure of the ramA gene has no similarity to other glycoside hydrolase sequences and possibly is the first member of a new enzyme family.
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PMID:The thermostable alpha-L-rhamnosidase RamA of Clostridium stercorarium: biochemical characterization and primary structure of a bacterial alpha-L-rhamnoside hydrolase, a new type of inverting glycoside hydrolase. 1063 87

Flavobacterium johnsonae was isolated as a microorganism that produced a beta-glucosidase with hydrolytic activity of beta-glucosyl ester linkages in steviol glycosides. The enzyme was purified to homogeneity from a cell-free extract by streptomycin treatment, ammonium sulfate fractionation, and column chromatographies on S-Sepharose and phenyl-Toyopearl. The molecular mass of the purified enzyme was about 72 kDa by SDS-PAGE. An isoelectric point of pI 8.8 was estimated by isoelectric focusing. The enzyme was most active at pH 7.0, and was stable between pH 3.0 and 9.0. The optimum temperature was 45 degrees C, and the enzyme was stable below 35 degrees C. The enzyme hydrolyzed glucosyl ester linkages at site 19 of rebaudioside A, stevioside, and rubusoside, although it could not degrad beta-glucosidic linkages at site 13 of rebaudioside B or steviol bioside. The enzyme acted on aryl beta-glucosides such as p-nitrophenyl beta-glucoside, phenyl betaglucoside, and salicin, and glucobioses such as sophorose and laminaribiose. The enzyme activity on Rub was inactivated completely by Hg2+, and reduced by Fe3+, Cu2+, p-chloromercuric benzoate, and phenylmethylsulfonyl fluoride (residual activity; 67.9-84.8%). The pNPG hydrolysis was also inactivated to almost the same degrees. Kinetic behaviors in the mixed substrate reactions of rebaudioside A and steviol monoside, and of steviol monoglucosyl ester and phenyl beta-glucoside suggested the glucosidic and glucosyl ester linkages were hydrolyzed at a single active site of the enzyme.
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PMID:Purification and some properties of a beta-glucosidase from Flavobacterium johnsonae. 1073 90

Cyclic hydroxamic acids and a glucosidase that occur in rye seedlings were investigated. The concentration of the glucoside of 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA-Glc) in shoots increased soon after germination and decreased to a lower, constant level as the plants started autotrophic growth. Cyclic hydroxamic acid glucoside beta-glucosidase activity also occurred transiently, and the timing of the increase and decrease was concurrent with that of cyclic hydroxamic acid glucosides. The glucosidase was isolated from 48-h-old rye shoots and purified to apparent homogeneity by using isoelectric precipitation, anion exchange chromatography, and gel filtration. The isoelectric point and the optimum reaction temperature were 4.9-5.1 and 25-30 degrees C, respectively. The N-terminal amino acid sequence was almost identical to that of the wheat glucosidases, but did not show any similarity to the sequences of other glucosidases of plant origin. SDS- and native-PAGE analyses showed that rye had several isozymes of glucosidase, and each isozyme was an oligomer of 60-kDa monomers with a molecular mass of approximately 300 kDa. The enzyme was highly active not only for DIMBOA-Glc but also for its 7-demethoxy analogue, DIBOA-Glc, which was different from the specificities of maize and wheat glucosidases.
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PMID:Purification and characterization of a beta-glucosidase from rye (Secale cereale L.) seedlings. 1077 41

The hyphomycete Chalara paradoxa CH32 produced an extracellular beta-glucosidase during the trophophase. The enzyme was purified to homogeneity by ion-exchange and size-exclusion chromatography. The purified enzyme had an estimated molecular mass of 170 kDa by size-exclusion chromatography and 167 kDa by SDS-PAGE. The enzyme had maximum activity at pH 4.0-5.0 and 45 degrees C. The enzyme was inactivated at 60 degrees C. At room temperature, it was unstable at acidic pH, but it was stable to alkaline pH. The purified enzyme was inhibited markedly by Hg(2+) and Ag(2+) and also to some extent by the detergents SDS, Tween 80, and Triton X-100 at 0.1%. Enzyme activity increased by 3-fold in the presence of 20% ethanol and to a lesser extent by other organic solvents. Purified beta-glucosidase was active against cellobiose and p-nitrophenyl-beta-D-glucopyranoside but did not hydrolyze lactose, maltose, sucrose, cellulosic substrates, or galactopyranoside, mannopyranoside, or xyloside derivatives of p-nitrophenol. The V(max) of the enzyme for p-NPG (K(m) = 0.52 mM) and cellobiose (K(m) = 0.58 mM) were 294 and 288.7 units/mg, respectively. Hydrolysis of pNPG was inhibited competitively by glucose (K(i) = 11.02 mM). Release of reducing sugars from carboxymethylcellulose by a purified endoglucanase produced by the same organism increased markedly in the presence of beta-glucosidase.
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PMID:Beta-glucosidase from Chalara paradoxa CH32: purification and properties. 1095 73


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