Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
Department of Fiber and Polymer Technology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
J Phys Chem B. 2021 Nov 4;125(43):11967-11979. doi: 10.1021/acs.jpcb.1c07293. Epub 2021 Oct 27.
Methylated carbohydrates are important from both biological and technical perspectives. Specifically, methylcellulose is an interesting cellulose derivative that has applications in foods, materials, cosmetics, and many other fields. While the molecular dynamics simulation technique has the potential for both advancing the fundamental understanding of this polymer and aiding in the development of specific applications, a general drawback is the lack of experimentally validated interaction potentials for the methylated moieties. In the present study, simulations using the GROMOS 56 carbohydrate force field are compared to NMR spin-spin coupling constants related to the conformation of the exocyclic torsion angle ω in d-glucopyranose and derivatives containing a 6-O-methyl substituent and a C-isotopologue thereof. A Karplus-type relationship is proposed for the C5-C6-O6-C torsion angle. Moreover, solvation free energies are compared to experimental data for small model compounds. Alkylation in the form of 6-O-methylation affects exocyclic torsion only marginally. Computed solvation free energies between nonmethylated and methylated molecules were internally consistent, which validates the application of these interaction potentials for more specialized purposes.
甲基化碳水化合物在生物学和技术方面都很重要。具体来说，甲基纤维素是一种有趣的纤维素衍生物，在食品、材料、化妆品和许多其他领域都有应用。虽然分子动力学模拟技术具有推进对这种聚合物的基本理解和辅助特定应用开发的潜力，但一个普遍的缺点是缺乏经过实验验证的用于甲基化部分的相互作用势能。在本研究中，使用 GROMOS 56 碳水化合物力场进行的模拟与与外环扭转角 ω 构象相关的 NMR 自旋-自旋耦合常数进行了比较，这些化合物包括含有 6-O-甲基取代基的 d-吡喃葡萄糖及其碳同位素类似物。提出了一种 C5-C6-O6-C 扭转角的 Karplus 型关系。此外，还将溶剂化自由能与小分子模型化合物的实验数据进行了比较。以 6-O-甲基化形式进行的烷基化仅对外环扭转产生微小影响。非甲基化和甲基化分子之间的计算溶剂化自由能具有内在一致性，这验证了这些相互作用势能在更专门的用途中的应用。
