French A D, Miller D P, Aabloo A
Southern Regional Research Center, New Orleans, Lousiana 70179.
Int J Biol Macromol. 1993 Feb;15(1):30-6. doi: 10.1016/s0141-8130(05)80085-6.
Miniature crystal models of cellulose and other carbohydrates were evaluated with the molecular mechanics program MM3. The models consisted of groups of 24 to 32 monosaccharide residues, with the models of mono- and disaccharides based on well-established, single-crystal work. Structures of the cellulose forms and cellotetraose were based on published work using fibre diffraction methods. A structure for the single-chain I alpha cellulose unit cell was also tested. A dielectric constant of about 4 was best for this type of work. Calculated intra- and intermolecular energy for glucose agreed with literature values for the heat of combustion. Cellulose II had the lowest calculated energy for a cellulose form, followed by I alpha, cellulose III(I), ramie I, IV(II) and IV(I). Optimization of cellulose IV caused larger mean atomic movements from the original crystallographic positions than the other cellulose forms, and cellotetraose had larger movements than any of the other structures. Lattice energies for the cellulose forms were about 20 kcal/mol of glucose residues, with a dominant van der Waals component.
使用分子力学程序MM3对纤维素和其他碳水化合物的微型晶体模型进行了评估。这些模型由24至32个单糖残基组成，单糖和二糖模型基于已确立的单晶研究。纤维素形式和纤维四糖的结构基于使用纤维衍射方法的已发表研究。还测试了单链Iα纤维素晶胞的结构。对于这类工作，约4的介电常数最为合适。计算得到的葡萄糖分子内和分子间能量与燃烧热的文献值相符。纤维素II在所有纤维素形式中计算得到的能量最低，其次是Iα、纤维素III(I)、苎麻I、IV(II)和IV(I)。纤维素IV的优化导致平均原子相对于原始晶体学位置的移动比其他纤维素形式更大，而纤维四糖的移动比其他任何结构都大。纤维素形式的晶格能约为每摩尔葡萄糖残基20千卡，主要由范德华力组成。
