Dowd M K, Reilly P J, French A D
Department of Chemical Engineering, Iowa State University, Ames 50011.
Biopolymers. 1994 May;34(5):625-38. doi: 10.1002/bip.360340505.
Isoenergy surfaces were calculated for the alpha- and beta-anomers of isomaltose and gentiobiose, based on 46,656 conformers for each disaccharide. Low-energy regions exist for each of the three staggered positions about the C-5'-C-6' bonds, and known crystal structures lie in two of these regions. As expected, the molecular partition function showed greater flexibility for these three-bond-linked disaccharides than for comparable two-bond-linked structures. A model miniature crystal of gentiobiose accounts for most of the remaining structural differences between the modeled isolated molecule and the crystal structure. Based on models of isolated molecules of isomaltose and gentiobiose, the predicted Boltzmann-weighted nmr coupling constants were satisfactory, as were predicted optical rotations for gentiobiose.
基于每种二糖的46,656个构象异构体，计算了异麦芽糖和龙胆二糖的α-和β-异头物的等能面。围绕C-5'-C-6'键的三个交错位置中的每一个都存在低能区，已知的晶体结构位于其中两个区域。正如预期的那样，分子配分函数表明，与类似的双键连接结构相比，这些三键连接的二糖具有更大的灵活性。龙胆二糖的模型微型晶体解释了建模的孤立分子与晶体结构之间的大部分剩余结构差异。基于异麦芽糖和龙胆二糖的孤立分子模型，预测的玻尔兹曼加权核磁共振耦合常数令人满意，龙胆二糖的预测旋光度也是如此。
