Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3-4, 24118, Kiel, Germany.
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.
Chemistry. 2022 Oct 7;28(56):e202201544. doi: 10.1002/chem.202201544. Epub 2022 Aug 4.
The conformational properties of monosaccharides constitute fundamental features of oligosaccharides. While the energy landscape of monosaccharides can be altered by a specific biochemical environment or by chemical modifications, the analysis of resulting dynamic conformational equilibria is not feasible by experimental means alone. In this work, a series of β-d-xylopyranosides is used to outline how a combination of experimental NMR parameters and computed molecular properties can be used to determine conformers and quantify the composition of conformational equilibria. We demonstrate that identifying the most stable conformers using energy calculations is challenging and computing of NMR shieldings is typically not sensitive enough. On the other hand, computed spin-spin coupling constants for the xyloside ring can be used to unambiguously assign experimental NMR data of dynamic conformational equilibria and quantify the ratio of different conformers in the mixture. As a proof of principle, this procedure allowed to analyze a hitherto unknown dynamic equilibrium of a diamino-xyloside as a precursor of a molecular switch.
单糖的构象性质构成了寡糖的基本特征。虽然单糖的能量景观可以通过特定的生化环境或化学修饰来改变，但仅通过实验手段分析由此产生的动态构象平衡是不可行的。在这项工作中，一系列β-D-吡喃木糖苷被用来概述如何将实验 NMR 参数和计算分子性质相结合，以确定构象体并定量构象平衡的组成。我们证明，使用能量计算来识别最稳定的构象体具有挑战性，并且计算 NMR 屏蔽通常不够敏感。另一方面，木糖苷环的计算自旋-自旋偶合常数可用于明确分配动态构象平衡的实验 NMR 数据，并定量混合物中不同构象体的比例。作为原理的证明，该程序允许分析一种 hitherto 未知的二氨基木糖苷的动态平衡，作为分子开关的前体。
