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Purification and biochemical characterization of a mycelial glucose- and xylose-stimulated β-glucosidase from the thermophilic fungus Humicola insolens

Paper ID Volume ID Publish Year Pages File Format Full-Text
35034 45069 2010 7 PDF Available
Title
Purification and biochemical characterization of a mycelial glucose- and xylose-stimulated β-glucosidase from the thermophilic fungus Humicola insolens
Abstract

A mycelial β-glucosidase from the thermophilic mold Humicola insolens was purified and biochemically characterized. The enzyme showed carbohydrate content of 21% and apparent molecular mass of 94 kDa, as estimated by gel filtration. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed a single polypeptide band of 55 kDa, suggesting that the native enzyme was a homodimer. Mass spectrometry analysis showed amino acid sequence similarity with a β-glucosidase from Humicola grisea var. thermoidea, with about 22% coverage. Optima of temperature and pH were 60 °C and 6.0–6.5, respectively. The enzyme was stable up to 1 h at 50 °C and showed a half-life of approximately 44 min at 55 °C. The β-glucosidase hydrolyzed cellobiose, lactose, p-nitrophenyl-β-d-glucopyranoside, p-nitrophenyl-β-d-fucopyranoside, p-nitrophenyl-β-d-xylopyranoside, p-nitrophenyl-β-d-galactopyranoside, o-nitrophenyl-β-d-galactopyranoside, and salicin. Kinetic studies showed that p-nitrophenyl-β-d-fucopyranoside and cellobiose were the best enzyme substrates. Enzyme activity was stimulated by glucose or xylose at concentrations up to 400 mM, with maximal stimulatory effect (about 2-fold) around 40 mM. The high catalytic efficiency for the natural substrate, good thermal stability, strong stimulation by glucose or xylose, and tolerance to elevated concentrations of these monosaccharides qualify this enzyme for application in the hydrolysis of cellulosic materials.

Keywords
β-Glucosidase; β-Glycosidase; Cellobiase; Glucose-stimulated β-glucosidase; Glucose-stimulated β-glycosidase; Humicola insolens
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Purification and biochemical characterization of a mycelial glucose- and xylose-stimulated β-glucosidase from the thermophilic fungus Humicola insolens
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 45, Issue 2, February 2010, Pages 272–278
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