Characterization of a Theme C Glycoside Hydrolase Family 9 Endo-Beta-Glucanase from a Biogas Reactor Metagenome |
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Authors: | Carola Schröder Christin Burkhardt Philip Busch Georg Schirrmacher Jörg Claren Garabed Antranikian |
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Affiliation: | 1.Institute of Technical Microbiology,Hamburg University of Technology (TUHH),Hamburg,Germany;2.Clariant Produkte (Deutschland) GmbH, Group Biotechnology,Munich,Germany |
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Abstract: | From a biogas reactor metagenome an ORF (bp_cel9A) encoding a bacterial theme C glycoside hydrolase family 9 (GH9) enzyme was recombinantly produced in E. coli BL21 pQE-80L. BP_Cel9A exhibited?≤?55% identity to annotated sequences. Subsequently, the enzyme was purified to homogeneity by affinity chromatography. The endo-beta-glucanase BP_Cel9A hydrolyzed the beta-1,3–1,4-linked barley beta-glucan with 24 U/mg at 30 °C and pH 6.0. More than 62% of activity was measured between 10 and 40 °C. Lichenan and xyloglucan were hydrolyzed with 67% and 40% of activity, respectively. The activity towards different substrates varied with different temperatures. However, the enzyme activity on CMC was extremely low (>?1%). In contrast to BP_Cel9A, most GH9 glucanases act preferably on crystalline or soluble cellulose with only side activities towards related substrates. The addition of calcium or magnesium enhanced the activity of BP_Cel9A, especially at higher temperatures. EDTA inhibited the enzyme, whereas EGTA had no effect, suggesting that Mg2+ may adopt the function of Ca2+. BP_Cel9A exhibited a unique substrate spectrum when compared to other GH9 enzymes with great potential for mixed-linked glucan or xyloglucan degrading processes at moderate temperatures. |
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