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Purification and enzymatic characterization of secretory glycoside hydrolase family 3 (GH3) aryl β-glucosidases screened from Aspergillus oryzae genome

Paper ID Volume ID Publish Year Pages File Format Full-Text
20048 43155 2015 10 PDF Available
Title
Purification and enzymatic characterization of secretory glycoside hydrolase family 3 (GH3) aryl β-glucosidases screened from Aspergillus oryzae genome
Abstract

By a global search of the genome database of Aspergillus oryzae, we found 23 genes encoding putative β-glucosidases, among which 10 genes with a signal peptide belonging to glycoside hydrolase family 3 (GH3) were overexpressed in A. oryzae using the improved glaA gene promoter. Consequently, crude enzyme preparations from three strains, each harboring the genes AO090038000223 (bglA), AO090103000127 (bglF), and AO090003001511 (bglJ), showed a substrate preference toward p-nitrophenyl-β-d-glucopyranoside (pNPGlc) and thus were purified to homogeneity and enzymatically characterized. All the purified enzymes (BglA, BglF, and BglJ) preferentially hydrolyzed aryl β-glycosides, including pNPGlc, rather than cellobiose, and these enzymes were proven to be aryl β-glucosidases. Although the specific activity of BglF toward all the substrates tested was significantly low, BglA and BglJ showed appreciably high activities toward pNPGlc and arbutin. The kinetic parameters of BglA and BglJ for pNPGlc suggested that both the enzymes had relatively higher hydrolytic activity toward pNPGlc among the fungal β-glucosidases reported. The thermal and pH stabilities of BglA were higher than those of BglJ, and BglA was particularly stable in a wide pH range (pH 4.5–10). In contrast, BglJ was the most heat- and alkaline-labile among the three β-glucosidases. Furthermore, BglA was more tolerant to ethanol than BglJ; as a result, it showed much higher hydrolytic activity toward isoflavone glycosides in the presence of ethanol than BglJ. This study suggested that the mining of novel β-glucosidases exhibiting higher activity from microbial genome sequences is of great use for the production of beneficial compounds such as isoflavone aglycones.

Keywords
Aspergillus oryzae; β-Glucosidase; Glycoside hydrolase family 3 (GH3); Aryl β-glucoside; Isoflavone aglycone
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Purification and enzymatic characterization of secretory glycoside hydrolase family 3 (GH3) aryl β-glucosidases screened from Aspergillus oryzae genome
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 120, Issue 6, December 2015, Pages 614–623
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us