| 1. |
- Enebro, Jonas, 1979-, et al.
(författare)
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A New Approach for Studying Correlations between the Chemical Structure and the Rheological Properties in Carboxymethyl Cellulose
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 8:10, s. 3253-3257
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Tidskriftsartikel (refereegranskat)abstract
- Two model sodium carboxymethyl celluloses (CMC) with similar monomer composition but with significant differences in the viscoelastic properties, that could not be assigned to variations in the average molar mass or molar mass distribution, were investigated with respect to the fraction of nonsubstituted cellulose segments in the polymers. The CMCs were hydrolyzed by a purified highly selective endoglucanase. The average molar mass and molar mass distribution of the enzyme products, as measured by size-exclusion chromatography with online multi-angle light scattering and refractive index detection (SEC/MALS/RI), revealed that the enzyme-catalyzed hydrolysis was more effective on one of the CMCs. To investigate whether this was due to a higher fraction of nonsubstituted cellulose segments in the polymer, the concentrations of nonsubstituted enzyme products, e.g., cellotetraose and cellopentaose, were measured by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). It was concluded that the two CMCs displayed significant differences in the fraction of nonsubstituted cellulose segments. Furthermore, the CMC with the strongest attractive intermolecular interactions, according to rheometry, also contained the highest fraction of nonsubstituted cellulose segments.
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| 2. |
- Enebro, Jonas, 1979-, et al.
(författare)
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Investigation of endoglucanase selectivity on carboxymethyl cellulose by mass spectrometric techniques
- 2009
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 16:2, s. 271-280
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Tidskriftsartikel (refereegranskat)abstract
- The benefits of applying cellulose selective enzymes as analytical tools for chemical structure characterization of cellulose derivatives have been frequently addressed over the years. In a recent study the high selectivity of cellulase Cel45A from Trichoderma reesei (Tr Cel45A) was utilized for relating the chemical structure to the flow properties of carboxymethyl cellulose (CMC). However, in order to take full advantage of the enzymatic hydrolysis the enzyme selectivity on the cellulose substrate must be further investigated. Therefore, the selectivity of Tr Cel45A on CMC was studied by chemical sample preparation of the enzyme products followed by mass spectrometric chemical structure characterization. The results strongly suggest that, in accordance with recent studies, also this highly selective endoglucanase is able to catalyze hydrolysis of glucosidic bonds adjacent to mono-substituted anhydroglucose units (AGUs). Furthermore, the results also indicate that substituents on the nearby AGUs will affect the hydrolysis.
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| 3. |
- Enebro, Jonas, 1979-, et al.
(författare)
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Liquid Chromatography combined with Mass Spectrometry for the Investigation of Endoglucanase Selectivity on Carboxymethyl Cellulose
- 2009
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 344:16, s. 2173-2181
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Tidskriftsartikel (refereegranskat)abstract
- Endoglucanases are useful tools in the chemical structure analysis of cellulose derivatives. However, knowledge on the endoglucanase selectivity, which is of central importance for data interpretation, is still limited. In this study, new reverse-phase liquid chromatography mass spectrometry (LC-MS) methods were developed to investigate the selectivity of the endoglucanases Cel5A, cel7B, Cel45A, and Cel74A from the filamentous fungus Trichoderma reesei. The aim was to improve the identification of the regioisomers in the complex mixtures that are obtained after enzymatic hydrolysis. Reduction followed by per-O-methylation was performed in order to improve the separation in reverse-phase LC, increase MS sensitivity, and to facilitate structure analysis by MS/MS of O-carboxymethyl glucose and cellooligosaccharides. The cellulose selective enzymes that were investigated displayed interesting differences in enzyme selectivity on CMC substrates.
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| 4. |
- Öhgren, Karin, et al.
(författare)
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High temperature enzymatic prehydrolysis prior to simultaneous saccharification and fermentation of steam pretreated corn stover for ethanol production
- 2007
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 40:4, s. 607-613
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Tidskriftsartikel (refereegranskat)abstract
- As a consequence of heightened concern for the greenhouse effect, depleting oil reserves and skyrocketing oil prices, renewable fuels, Such as bioethanol, are becoming increasingly important. Cellulosic biomass like wood, agricultural residue and herbaceous material is a huge, cheap natural resource that can be used for ethanol production. Decreasing production costs through technological development is, however, still needed to make ethanol from cellulosics economically feasible. In this study, the effect on overall ethanol yield of an enzymatic prehydrolysis prior to simultaneous saccharification and fermentation (SSF) of steam pretreated corn stover was investigated. Two enzyme mixtures were utilised. A mixture of commercially available enzymes (Novozymes A/S, Baegersvaerd, Denmark) was compared with a developmental thermo-active cellulase complex produced by Roal Oy (Rajam&i, Finland). The thermoactive preparation comprised three essential cellulases and one xylanase enzyme. The prehydrolysis was, under the conditions evaluated, found to have no or negative effect on the overall ethanol yield. Longer prehydrolysis time resulted in a larger decrease in overall ethanol yield than shorter prehydrolysis. Using the experimental thermo-active enzyme mixture was shown to give a higher glucose concentration after prehydrolysis than when the commercial enzyme mixture was used in similar experiments. The highest ethanol concentration, 33.8 g/L, was reached in the SSF with 11.5% water-insoluble substances using the developmental thermoactive cellulase complex, and 1.8 g/L compressed baker's yeast. This concentration corresponded to 80.2% overall ethanol yield based on the glucose content in the raw material. However, if the xylose present in the beer at the end of the SSF could be fermented to ethanol, another 12.6 g ethanol/L could theoretically be produced (0.51 g ethanol/g xylose). (c) 2006 Elsevier Inc. All rights reserved.
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