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dc.contributor.authorPatchett, Mark L.
dc.contributor.authorDaniel, Roy M.
dc.contributor.authorMorgan, Hugh W.
dc.identifier.citationPatchett, M.L., Daniel, R.M. & Morgan, H.W. (1987). Purification and properties of a stable beta-glucosidase from an extremely thermophilic anaerobic bacterium. Biochemical Journal, 243(3), 779-787.en_NZ
dc.description.abstractA beta-glucosidase (EC was purified to homogeneity from cell-free extracts of an extremely thermophilic anaerobic bacterium. The enzyme has an Mr of 43,000 as determined by molecular-exclusion chromatography, has a pI of 4.55 and shows optimum activity at pH 6.2. The enzyme is active against a wide range of aryl beta-glycosides and beta-linked disaccharides, with beta-galactosidase activity only slightly less than beta-glucosidase activity, and significant beta-xylosidase activity. Lineweaver-Burk plots for p-nitrophenyl beta-glucoside, o-nitrophenyl beta-glucoside and cellobiose substrates are biphasic concave-downwards. Inhibition of the beta-glucosidase by substrates and glucose is negligible. Thermal inactivation follows first-order kinetics, with t1/2 (65 degrees C) 45 h, t1/2 (75 degrees C) 47 min and t1/2 (85 degrees C) 1.4 min and a deactivation energy of 380 kJ/mol at pH 6.2. At pH 7.0, which is the optimum pH for thermostability, t1/2 (75 degrees C) is 130 min. At 75 degrees C, at pH 6.2, the thermostability is enhanced about 8-fold by 10% (w/v) glycerol, about 6-fold by 0.2 M-cellobiose and about 3-fold by 5 mM-dithiothreitol and 5 mM-2-mercaptoethanol.en_NZ
dc.titlePurification and properties of a stable beta-glucosidase from an extremely thermophilic anaerobic bacterium.en_NZ
dc.typeJournal Articleen_NZ

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