Institute of Medical Biochemistry Leopoldo de Meis, University Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21941, RJ, Brazil.
BioMolecular Sciences Department, School of Pharmacy, University of Mississippi, University, 38677 MS, USA.
J Struct Biol. 2020 Jan 1;209(1):107407. doi: 10.1016/j.jsb.2019.107407. Epub 2019 Nov 4.
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(SO)-α(1-3)-l-Fucp2,4(SO)-α(1-3)-l-Fucp2(SO)-α(1-3)-l-Fucp2(SO)] and the composing monosaccharide unit Fucp, primarily by nuclear magnetic resonance (NMR) experiments performed at very low temperatures and using HO 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 H-H 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.
尽管碳水化合物的 3D 结构已知有助于其生物功能，但糖的构象研究具有挑战性，因为其链在溶液中是柔性的，因此 3D 结构约束的数量有限。在这里，我们研究了由以下结构组成的 Lytechinus variegatus 硫酸化岩藻聚糖的四糖构建块的构象性质：[l-Fucp4(SO)-α(1-3)-l-Fucp2,4(SO)-α(1-3)-l-Fucp2(SO)-α(1-3)-l-Fucp2(SO)] 和组成的单糖单元 Fucp，主要通过在非常低的温度下进行核磁共振 (NMR) 实验，并使用 HO 作为糖的溶剂，而不是使用常规的重水。通过减慢快速的化学交换速率并迫使不稳定位点质子化，我们增加了可以通过 NMR 光谱测量的通过空间 H-H 距离的数量。通过这种策略，获得了溶液中四糖和 l-Fucp 的更多构象细节。进行了计算分子动力学以补充和验证基于 NMR 的测量。提供了 NMR 约束 3D 结构的四糖模型。
