A Novel [beta]-Glucosidase from Humicola insolens with High Potential for Untreated Waste Paper Conversion to Sugars
Humicola insolens produced a new [beta]-glucosidase (BglHi2) under solid-state fermentation. The purified enzyme showed apparent molecular masses of 116 kDa (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and 404 kDa (gel-filtration), suggesting that it is a homotetramer. Mass spectromet...
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Veröffentlicht in: | Applied biochemistry and biotechnology 2014-05, Vol.173 (2), p.391 |
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Zusammenfassung: | Humicola insolens produced a new [beta]-glucosidase (BglHi2) under solid-state fermentation. The purified enzyme showed apparent molecular masses of 116 kDa (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and 404 kDa (gel-filtration), suggesting that it is a homotetramer. Mass spectrometry analysis showed amino acid sequence similarity with a [beta]-glucosidase from Chaetomium thermophilum. Optima of pH and temperature were 5.0 and 65 °C, respectively, and the enzyme was stable for 60 min at 50 °C, maintaining 71 % residual activity after 60 min at 55 °C. BglHi2 hydrolyzed p-nitrophenyl-[beta]-d-glucopyranoside and cellobiose. Cellobiose hydrolysis occurred with high apparent affinity (K ^sub M^=0.24±0.01 mmol L^sup -1^) and catalytic efficiency (k ^sub cat^/K ^sub M^=1,304.92±53.32 L mmol^sup -1^ s^sup -1^). The activity was insensitive to Fe^sup +3^, Cr^sup +2^, Mn^sup +2^, Co^sup +2^, and Ni^sup 2+^, and 50-60 % residual activities were retained in the presence of Pb^sup 2+^, Hg^sup 2+^, and Cu^sup 2+^. Mixtures of pure BglHi2 or H. insolens crude extract (CE) with crude extracts from Trichoderma reesei fully hydrolyzed Whatman no. 1 paper. Mixtures of H. insolens CE with T. reesei CE or Celluclast 1.5 L fully hydrolyzed untreated printed office paper, napkin, and magazine papers after 24-48 h, and untreated cardboard was hydrolyzed by a H. insolens CE/T. reesei CE mixture with 100 % glucose yield. Data revealed the good potential of BglHi2 for the hydrolysis of waste papers, promising feedstocks for cellulosic ethanol production.[PUBLICATION ABSTRACT] |
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ISSN: | 0273-2289 1559-0291 |
DOI: | 10.1007/s12010-014-0847-9 |