Although the 3D structure of carbohydrates is known to contribute to their biological roles, conformational studies of sugars are challenging because their chains are flexible in solution and consequently the number of 3D structural restraints is limited. Here, we investigate the conformational properties of the tetrasaccharide building block of the Lytechinus variegatus sulfated fucan composed of the following structure [l-Fucp4(SO3-)-α(1-3)-l-Fucp2,4(SO3-)-α(1-3)-l-Fucp2(SO3-)-α(1-3)-l-Fucp2(SO3-)] and the composing monosaccharide unit Fucp, primarily by nuclear magnetic resonance (NMR) experiments performed at very low temperatures and using H2O as the solvent for the sugars rather than using the conventional deuterium oxide. By slowing down the fast chemical exchange rates and forcing the protonation of labile sites, we increased the number of through-space 1H-1H distances that could be measured by NMR spectroscopy. Following this strategy, additional conformational details of the tetrasaccharide and l-Fucp in solution were obtained. Computational molecular dynamics was performed to complement and validate the NMR-based measurements. A model of the NMR-restrained 3D structure is offered for the tetrasaccharide.

中文翻译：

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左旋岩藻的L-岩藻糖的构象性质和硫酸化的L-岩藻糖的四糖结构单元。

尽管已知碳水化合物的3D结构有助于其生物学作用，但糖的构象研究仍具有挑战性，因为它们的链在溶液中具有柔性，因此3D结构约束的数量受到限制。在这里，我们研究了由以下结构[1-Fucp4（SO3-）-α（1-3）-I-Fucp2,4（SO3-）-α组成的变异扁豆Lytechinus硫酸化fucan的四糖构件的构象性质。 （1-3）-1-Fucp2（SO3-）-α（1-3）-Fucp2（SO3-）]和组成单糖单元Fucp，主要是通过在非常低的温度下进行的核磁共振（NMR）实验并且使用H2O作为糖类的溶剂，而不是使用常规的氘化de。通过减慢化学物质的快速交换速度并强迫不稳定部位的质子化，我们增加了可以通过NMR光谱法测量的贯穿空间的1H-1H距离的数量。按照这种策略，获得了溶液中四糖和1-Fucp的其他构象细节。进行计算分子动力学以补充和验证基于NMR的测量。为四糖提供了NMR约束的3D结构模型。