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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)

beta-glucosidase (EC 3.2.1.21) was isolated from the culture filtrate of Aspergillus niger IBT-90. The crude extracellular enzyme preparation was fractionated by six step purification procedure, (NH4)2SO4 precipitation, gel filtration on Bio-Gel P-10 and P-100, an ion-exchange chromatography on DEAE Bio-Gel A, yielding beta-glucosidase with an isoelectric point at pH 4.05. The enzyme was found to be a dimer with an apparent molecular weight of approximately 200 kDa as determined by size exclusion chromatography. It is composed of two apparently identical subunits of about 100 kDa (determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis). A. niger IBT-90 beta-glucosidase contains 33% carbohydrates. It is most active towards cellobiose at pH 4.8 and 65 degrees C. The enzyme sequentially splits off glucose units from non reducing ends of collodextrins. Kinetic studies on cellobiose and salicin hydrolysis, in concentration from 0.1 to 5.0 mM, resulted in non-linear Lineweaver-Burk and Hanes plots, whereas p-nitrophenyl-beta-D-glucopiranoside (pNPG) did not induce this type of effect. No metal ion is required for the enzyme catalytic activity. Hg2+ and N-bromosuccinimide (NBS) are its strong inhibitors. Glucono-delta-lactone and glucose are competitive inhibitors of the enzyme and glucono-delta-lactone is more potent of the two.
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PMID:Purification and some properties of beta-glucosidase from Aspergillus niger IBT-90. 942 94

The growth and preference for utilisation of various sugar by the Penicillium species Penicillium pinophilum IBT 4186, Penicillium persicinum IBT 13226 and Penicillium brasilianum IBT 20888 was studied in batch cultivations using various monosaccharides as carbon source, either alone or in mixtures. P. pinophilum IBT 4186 and P. persicinum IBT 13226 had a micro(max) around 0.08-0.09 h(-1) using either glucose or xylose as carbon source. The micro(max) of P. brasilianum IBT 20888 was 0.16 and 0.14 h(-1) on glucose and xylose, respectively. Glucose was found to exert repression on the catabolism of mannose, galactose, xylose and arabinose. The three species were able to utilise all the tested monosaccharides, but arabinose was only slowly metabolised. Glucose was also found to repress the production of endoglucanases, endoxylanases and beta-xylosidases. After glucose depletion, the fungi started producing beta-glucosidase and endoglucanases. Xylose did not repress the enzyme production and it induced the production of endoxylanases and beta-xylosidases.
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PMID:Growth and enzyme production by three Penicillium species on monosaccharides. 1506 67