- High Yielding Acid-Catalysed Hydrolysis of Cellulosic Polysaccharides and Native Biomass into Low Molecular Weight Sugars in Mixed Ionic Liquid Systems
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Ionic media comprising 1-butyl-3-methylimidazolium chloride and the acidic deep eutectic solvent choline chloride/oxalic acid as co-solvent-catalyst, very efficiently convert various cellulosic substrates, including native cellulosic biomass, into water-soluble carbohydrates. The optimum reaction systems yield a narrow range of low molecular weight carbohydrates directly from cellulose, lignocellulose, or algal saccharides, in high yields and selectivities up to 98 %. Cellulose possesses significant potential as a renewable platform from which to generate large volumes of green replacements to many petrochemical products. Within this goal, the production of low molecular weight saccharides from cellulosic substances is the key to success. Native cellulose and lignocellulosic feedstocks are less accessible for such transformations and depolymerisation of polysaccharides remains a primary challenge to be overcome. In this study, we identify the catalytic activity associated with selected deep eutectic solvents that favours the hydrolysis of polysaccharides and develop reaction conditions to improve the outcomes of desirable low molecular weight sugars. We successfully apply the chemistry to raw bulk, non-pretreated cellulosic substances.
- Bodachivskyi, Iurii,Kuzhiumparambil, Unnikrishnan,Bradley G. Williams
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p. 1316 - 1324
(2019/11/11)
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- Cloning, expression and biochemical characterization of a GH1 β-glucosidase from Cellulosimicrobium cellulans
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β-Glucosidase plays an important role in the degradation of cellulose. In this study, a novel β-glucosidase ccbgl1b gene for a glycosyl hydrolase (GH) family 1 enzyme was cloned from the genome of Cellulosimicrobium cellulans and expressed in Escherichia coli BL21 cells. The sequence contained an open reading frame of 1494 bp, encoded a polypeptide of 497 amino acid residues. The recombinant protein CcBgl1B was purified by Ni sepharose fastflow affinity chromatography and had a molecular weight of 57 kDa, as judged by SDS-PAGE. The optimum β-glucosidase activity was observed at 55 °C and pH 6.0. Recombinant CcBgl1B was found to be most active against aryl-glycosides p-nitrophenyl-β-D-glucopyranoside (pNPβGlc), followed by p-nitrophenyl-β-D-galactopyranoside (pNPβGal). Using disaccharides as substrates, the enzyme efficiently cleaved β-linked glucosyl-disaccharides, including sophorose (β-1,2-), laminaribiose (β-1,3-) and cellobiose (β-1,4-). In addition, a range of cello-oligosaccharides including cellotriose, cellotetraose and cellopentaose were hydrolysed by CcBgl1B to produce glucose. The interaction mode between the enzyme and the substrates driving the reaction was modelled using a molecular docking approach. Understanding how the GH1 enzyme CcBgl1B from C. cellulans works, particularly its activity against cello-oligosaccharides, would be potentially useful for biotechnological applications of cellulose degradation.
- Yuan, Ye,Xu, Fenghua,Yao, Jianzhuang,Hu, Yanho,Wang, Jiao,Zhao, Tianjiao,Zhou, Yifa,Gao, Juan
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p. 362 - 371
(2017/11/03)
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- Regioselective glucosylation of inositols catalyzed by Thermoanaerobacter sp. CGTase
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Monoglucosylated products of l-chiro-, d-chiro-, muco-, and allo-inositol were synthesized by regioselective α-d-glucosylation with cyclodextrin glucosyl transferase from Thermoanaerobacter sp. after hydrolysis of by products with Aspergillus niger glucoamylase. While the reactions carried out with d-chiro-, muco-, and allo-inositol resulted in the regioselective formation of monoglucosylated products, two products were obtained in the reaction with l-chiro-inositol. Through the structural characterization of the glucosylated inositols here we demonstrated that the selectivity observed in the glucosylation of several inositols by Thermoanaerobacter sp. CGTase, is analogous to the specificity observed for the glucosylation of β-d-glucopyranose and equivalent glucosides.
- Miranda-Molina, Alfonso,Marquina-Bahena, Silvia,Alvarez, Laura,Lopez-Munguia, Agustin,Castillo, Edmundo
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p. 93 - 101,9
(2020/08/20)
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- Enzymatic synthesis of cellulose II-like substance via cellulolytic enzyme-mediated transglycosylation in an aqueous medium
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The enzymatic synthesis of cellulose-like substance via a non-biosynthetic pathway has been achieved by transglycosylation in an aqueous system of the corresponding substrate, cellotriose for cellulolytic enzyme endo-acting endoglucanase I (EG I) from Hypocrea jecorina. A significant amount of water-insoluble product precipitated out from the reaction system. MALDI-TOF mass analysis showed that the resulting precipitate had a degree of polymerization (DP) of up to 16 from cellotriose. Solid-state 13C NMR spectrum of the resulting water-insoluble product revealed that all carbon resonance lines were assigned to two kinds of anhydroglucose residues in the corresponding structure of cellulose II. X-ray diffraction (XRD) measurement as well as 13C NMR analysis showed that the crystal structure corresponds to cellulose II with a high degree of crystallinity. We propose the multiple oligomers form highly crystalline cellulose II as a result of self-assembly via oligomer-oligomer interaction when they precipitate.
- Hattori, Takeshi,Ogata, Makoto,Kameshima, Yumiko,Totani, Kazuhide,Nikaido, Mitsuru,Nakamura, Takashi,Koshino, Hiroyuki,Usui, Taichi
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scheme or table
p. 22 - 26
(2012/07/02)
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