Purification and characterization of an extracellular β-glucosidase from the thermophilic fungus Sporotrichum thermophile and its influence on cellulase activity

Bhat, Mahalingeshwara K and Gaikwad, Joel Solomon and Maheshwari, Ramesh (1993) Purification and characterization of an extracellular β-glucosidase from the thermophilic fungus Sporotrichum thermophile and its influence on cellulase activity. In: Journal of General Microbiology, 139 . pp. 2825-2832.

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Abstract

Multiple forms of beta-glucosidase (EC 3.2.1.21) of Sporotrichum thermophile were produced when the fungus was grown in a cellulose medium. One beta-glucosidase was purified 16-fold from 6-d-old culture filtrates by ion-exchange and gel-filtration chromatography. The purified enzyme was free of cellulase activity. It hydrolysed aryl beta-D-glucosides and beta-D-linked diglucosides. It was optimally active at pH 5.4, at 65-degrees-C. The apparent K(m) values for p-nitrophenyl beta-D-glucoside (PNPG) and cellobiose were 0.29 and 0.83 mm, respectively. Glucose, fucose, nojirimycin and gluconolactone inhibited beta-glucosidase competitively. At high (> 1 mm) substrate concentration, beta-glucosidase catalysed a parallel transglycosylation reaction. The transglycosylation product formed from cellobiose appeared to be a beta-linked tetramer of glucose. Admixtures of beta-glucosidase and cellulase components showed that the concept of cellobiose inhibition of cellulases was not valid for all components of the cellulase system of S. thermophile. Beta-Glucosidase supplementation also stimulated cellulose hydrolysis by cellulases when there was no accumulation of cellobiose in reaction mixture.

Item Type:	Journal Article
Publication:	Journal of General Microbiology
Publisher:	Society for General Microbiology
Additional Information:	Copyright of this article belongs to Society for General Microbiology.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	24 Feb 2011 05:38
Last Modified:	24 Feb 2011 05:38
URI:	http://eprints.iisc.ac.in/id/eprint/35716

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