Coarse-Grained Model for the Interconversion between Native and Liquid Ammonia-Treated Crystalline Cellulose

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• 作者：Giovanni Bellesia ; Shishir P. S. Chundawat ; Paul Langan ; Antonio Redondo ; Bruce E. Dale ; S. Gnanakaran
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：July 19, 2012
• 年：2012
• 卷：116
• 期：28
• 页码：8031-8037
• 全文大小：427K
• 年卷期：v.116,no.28(July 19, 2012)
• ISSN：1520-5207

文摘

We present the results of Langevin dynamics simulations on a coarse鈥揼rained model for a structural transition in crystalline cellulose pertinent to the cellulose degradation problem. We analyze two different cellulose crystalline forms: cellulose I<sub>尾sub> (the natural form of cellulose) and cellulose III<sub>Isub> (obtained after cellulose I<sub>尾sub> is treated with anhydrous liquid ammonia). Cellulose III<sub>Isub> has been the focus of wide interest in the field of cellulosic biofuels, as it can be efficiently hydrolyzed to readily fermentable glucose (its enzymatic degradation rates are up to 5-fold higher than those of cellulose I<sub>尾sub>). The coarse-grained model presented in this study is based on a simplified geometry and on an effective potential mimicking the changes in both intracrystalline hydrogen bonds and stacking interactions during the transition from cellulose I<sub>尾sub> to cellulose III<sub>Isub>. The model reproduces both structural and thermomechanical properties of cellulose I<sub>尾sub> and III<sub>Isub>. The work presented herein describes the structural transition from cellulose I<sub>尾sub> to cellulose III<sub>Isub> as driven by the change in the equilibrium state of two degrees of freedom in the cellulose chains. The structural transition from cellulose I<sub>尾sub> to cellulose III<sub>Isub> is essentially reduced to a search for optimal spatial arrangement of the cellulose chains.