Ames Laboratory, ‡Department of Chemistry, §Chemical and Biological Engineering Department, Iowa State University , Ames, Iowa 50011, United States.
J Phys Chem B. 2013 Sep 12;117(36):10430-43. doi: 10.1021/jp406266u. Epub 2013 Aug 28.
Biomass recalcitrance, the resistance of cellulosic biomass to degradation, is due in part to the stability of the hydrogen bond network and stacking forces between the polysaccharide chains in cellulose microfibers. The fragment molecular orbital (FMO) method at the correlated Møller-Plesset second order perturbation level of theory was used on a model of the crystalline cellulose Iα core with a total of 144 glucose units. These computations show that the intersheet chain interactions are stronger than the intrasheet chain interactions for the crystalline structure, while they are more similar to each other for a relaxed structure. An FMO chain pair interaction energy decomposition analysis for both the crystal and relaxed structures reveals an intricate interplay between electrostatic, dispersion, charge transfer, and exchange repulsion effects. The role of the primary alcohol groups in stabilizing the interchain hydrogen bond network in the inner sheet of the crystal and relaxed structures of cellulose Iα, where edge effects are absent, was analyzed. The maximum attractive intrasheet interaction is observed for the GT-TG residue pair with one intrasheet hydrogen bond, suggesting that the relative orientation of the residues is as important as the hydrogen bond network in strengthening the interaction between the residues.
生物质抗降解性，即纤维素生物质对降解的抗性，部分归因于纤维素微纤维中多糖链之间氢键网络和堆积力的稳定性。在相关 Møller-Plesset 二级微扰理论水平上，使用片段分子轨道 (FMO) 方法对具有总共 144 个葡萄糖单元的结晶纤维素 Iα 核模型进行了计算。这些计算表明，对于结晶结构，层间链相互作用比层内链相互作用更强，而对于弛豫结构，它们彼此更相似。对于晶体和弛豫结构，FMO 链对相互作用能分解分析揭示了静电、色散、电荷转移和交换排斥效应之间的复杂相互作用。分析了在纤维素 Iα 的晶体和弛豫结构中，主醇基团在稳定内层链间氢键网络中的作用，其中不存在边缘效应。观察到具有一个层内氢键的 GT-TG 残基对的最大吸引层内相互作用，这表明残基的相对取向与氢键网络一样重要，可增强残基之间的相互作用。
