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 procedure is described for the preparation of extensively purified beta-D-glucosidase (EC 3.2.1.21) from the cytosol fraction of rat kidney. The specific activity of the beta-glucosidase in the high speed supernatant (100 000 X g, 90 min) fraction of rat kidney homogenate is 700-fold greater than that in the same fraction from heart, skeletal muscle, lung, spleen, brain or liver. beta-Glucosidase activity co-chromatographs with beta-D-galactosidase, beta-D-fucosidase, alpha-L-arabinosidase and beta-D-xylosidase activities through the last four column steps of the purification and their specific activities are 0.26, 0.39, 0.028 and 0.017 relative to that of beta-glucosidase, respectively. The specific activity of the apparently homogeneous beta-glucosidase is 115 000 nmol of glucose released from 4-methylumbelliferyl-beta-D-glucopyranoside per mg protein per h. All five glycosidase activities possess similar pH dependency (pH optimum, 6--7) and heat lability, and co-migrate on polyacrylamide disc gels at pH 8.9 (RF, 0.67). beta-Glucosidase acitivity is inhibited competitively by glucono-(1 leads to 5)-lactone (KI, 0.61 mM) and non-competitively by a variety of sulfhydryl reagents including N-ethylmaleimide, p-chloromercuribenzoate, 5,5'-dithio-bis(2-nitrobenzoic acid), and iodoacetic acid. Although the enzyme will release glucose from p-nitrophenyl and 4-methylumbelliferyl derivatives of beta-D-glucose, it will not hydrolyze xylosyl-O-serine, beta-D-glucocerebroside, lactose, galactosylovalbumin or trehalose. The enzyme consists of a single polypeptide chain with a molecular weight of 50 000--58 000, has a sedimentation coefficient of 4.41 S and contains a relatively large number of acidic amino acids. A study of the distribution of beta-glucosidase activity in various regions of the dissected rat kidney indicates that the enzyme is probably contained in cells of the proximal convoluted tubule. The enzyme is also present in relatively large amounts in the villus cells, but not crypt cells, of the intestine. The physiological substrate and function of the enzyme are unknown.
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PMID:Isolation and characterization of beta-glucosidase from the cytosol of rat kidney cortex. 0 4

An isoflavone conjugates hydrolyzing beta-glucosidase (ICHG) from endophytic bacterium, Pseudomonas ZD-8 was purified to homogeneity by successive ammonium sulfate precipitation, gel filtration on SephadexG-100, DEAE-sephrose CL-6B and DEAE-Sephacel chromatography. The enzyme was a monomeric protein with an apparent molecular mass of 33 kDa as determined by SDS-PAGE and gel filtration. It was optimally active at pH 6.0 and 40 degrees C and had a specific activity of 1485 U mg of protein(-1) against genistin. The ICHG readily hydrolyzed rho-nitrophenyl-beta-glucoside, rho-nitrophenyl-beta-galactoside, genistin, daidzin, with Km values of 1.64, 1.87, 0.012, 0.014 mM, respectively. The ICHG showed a pronounced specificity for glucose in the 7-position of isoflavone and flavone conjugates and hydrolyzed effectively malonyl isoflavone glucosides as well as isoflavone glucosides with similar kinetics. Glucose and glucono-delta-lactone inhibited the enzyme competitively with Ki values of 84 mM and 23 mM, respectively. The enzyme did not require divalent cations for activity, and its activity was strongly inhibited by Hg2+, Ag+, rho-chloromercuribenzoate, iodoacetic acid, and N-ethylmaleimide while reducing agents such as beta-mercaptoethanol, dithiothreitol, dithioerythritol, glutathione slightly activated the enzyme.
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PMID:Purification and characterization of an isoflavone-conjugates-hydrolyzing beta-glucosidase from endophytic bacterium. 1505 33

Maize (Zea mays L.) beta-glucosidase (beta-d-glucoside glucohydrolase, EC 3.2.1.21) was extracted from the coleoptiles of 5- to 6-day-old maize seedlings with 50 millimolar sodium acetate, pH 5.0. The pH of the extract was adjusted to 4.6, and most of the contaminating proteins were cryoprecipitated at 0 degrees C for 24 hours. The pH 4.6 supernatant from cryoprecipitation was further fractionated by chromatography on an Accell CM column using a 4.8 to 6.8 pH gradient of 50 millimolar sodium acetate, which yielded the enzyme in two homogeneous, chromatographically different fractions. Purified enzyme was characterized with respect to subunit molecular weight, isoelectric point, amino acid composition, NH(2)-terminal amino acid sequence, pH and temperature optima, thermostability, and activity and stability in the presence of selected reducing agents, metal ions, and alkylating agents. The purified enzyme has an estimated subunit molecular mass of 60 kilodaltons, isoelectric point at pH 5.2, and pH and temperature optima at 5.8 and 50 degrees C, respectively. The amino acid composition data indicate that the enzyme is rich in Glx and Asx, the sum of which approaches 25%. The sequence of the first 20 amino acids in the N-terminal region was H(2)N-Ser-Ala-Arg-Val-Gly-Ser-Gln-Asn-Gly-Val-Gln-Met-Leu-Ser-Pro-(Ser?) -Glu-Ile-Pro-Gln, and it shows no significant similarity to other proteins with known sequence. The enzyme is extremely stable at 0 to 4 degrees C up to 1 year but loses activity completely at and above 55 degrees C in 10 minutes. Likewise, the enzyme is stable in the presence of or after treatment with 500 millimolar 2-mercaptoethanol, and it is totally inactivated at 2000 millimolar 2-mercaptoethanol. Such metal ions as Hg(2+) and Ag(+) reversibly inhibit the enzyme at micromolar concentrations, and inhibition could be completely overcome by adding 2-mercaptoethanol at molar excess of the inhibitory metal ion. The alkylating agents iodoacetic acid and iodoacetamide irreversibly inactivate the enzyme and such inactivation is accelerated in the presence of urea.
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PMID:Purification and Partial Characterization of Maize (Zea mays L.) beta-Glucosidase. 1666 11