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Characterization of two extracellular β-glucosidases produced from the cellulolytic fungus Aspergillus sp. YDJ216 and their potential applications for the hydrolysis of flavone glycosides.

Author
Abstract
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A cellulolytic fungus YDJ216 was isolated from a compost and identified as an Aspergillus sp. strain. Two extracellular β-glucosidases, BGL1 and BGL2, were purified using ultrafiltration, ammonium sulfate fractionation, and High-Q chromatography. Molecular masses of BGL1 and BGL2 were estimated to be 97 and 45 kDa, respectively, by SDS-PAGE. The two enzymes eluted as one peak at 87 kDa by Sephacryl S-200 chromatography, and located at similar positions in a zymogram after intact gel electrophoresis, suggesting BGL1 and BGL2 might be monomeric and dimeric, respectively. The two enzymes showed similar enzymatic properties; they were optimally active at pH 4.0-4.5 and 60 °C, and had similar half-lives at 70 °C. Two enzymes also preferred p-nitrophenyl glucose (pNPG) with the same Km and hardly hydrolyzed cellobiose, suggesting BGL1 and BGL2 are aryl β-glucosidases. However, Vmax for pNPG of BGL1 (953.2 U/mg) was 14.3 times higher than that of BGL2 (66.5 U/mg). When tilianin (a flavone glycoside of acacetin) was reacted with both enzymes, inhibitory activity for monoamine oxidase, relating to oxidation of neurotransmitter amines, was increased closely to the degree obtained by acacetin. These results suggest that BGL1 and BGL2 could be used to hydrolyze flavone glycosides to improve their inhibitory activities.

Year of Publication
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2018
Journal
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International journal of biological macromolecules
Date Published
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2018
ISSN Number
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0141-8130
URL
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http://linkinghub.elsevier.com/retrieve/pii/S0141-8130(17)34742-6
DOI
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10.1016/j.ijbiomac.2018.01.020
Short Title
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Int J Biol Macromol
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