Le Questel J Y, Cros S, Mackie W, Pérez S
Ingénierie Moléculaire, Institut National de la Recherche Agronomique, Nantes, France.
Int J Biol Macromol. 1995 Jun;17(3-4):161-75. doi: 10.1016/0141-8130(95)92682-g.
In this study, X-ray crystallographic data of sulfated monosaccharides have been used to derive appropriate parameters for sulfate groups in the Tripos force field, previously parameterized for carbohydrates. A database of nine sulfated monosaccharides occurring as building blocks of sulfated polysaccharides such as carrageenans and sulfated glycosaminoglycans has been built. These tools have then been used to evaluate the conformational energies of the repeating units of the kappa-, iota- and lambda-carrageenan polymers, taking into account the rotation around the sulfate groups. In a third step, helical conformations of carrageenans have been explored and the results compared with the experimental data obtained by X-ray fibre diffraction. Stable, single, right-handed helices, with geometric and helical parameters in close correspondence with the best models derived from X-ray diffraction data, have been generated. Finally, the configurational statistics of random-coil carrageenan chains have been investigated and compared with experimental data currently available on these polymers. A highly flexible character is predicted for kappa- and iota-carrageenans, with lambda-carrageenan showing slightly more extension.
在本研究中，硫酸化单糖的X射线晶体学数据已被用于推导Tripos力场中硫酸根的合适参数，该力场先前已针对碳水化合物进行了参数化。已建立了一个包含九种硫酸化单糖的数据库，这些单糖作为硫酸化多糖（如角叉菜胶和硫酸化糖胺聚糖）的构建单元。然后，利用这些工具评估κ-、ι-和λ-角叉菜胶聚合物重复单元的构象能，同时考虑硫酸根周围的旋转。第三步，探索了角叉菜胶的螺旋构象，并将结果与通过X射线纤维衍射获得的实验数据进行比较。已生成稳定的单右手螺旋，其几何和螺旋参数与从X射线衍射数据得出的最佳模型密切对应。最后，研究了无规卷曲角叉菜胶链的构型统计，并与目前这些聚合物的实验数据进行了比较。预测κ-和ι-角叉菜胶具有高度的柔性，而λ-角叉菜胶的伸展性略强。
