The diversity in molecular arrangements and dynamics displayed by glycans renders traditional NMR strategies, employed for proteins and nucleic acids, insufficient. Because of the unique properties of glycans, structural studies often require the adoption of a different repertoire of tailor-made experiments and protocols. We present an account of recent developments in NMR techniques that will deepen our understanding of structure-function relations in glycans. We open with a survey and comparison of methods utilized to determine the structure of proteins, nucleic acids and carbohydrates. Next, we discuss the structural information obtained from traditional NMR techniques like chemical shifts, NOEs/ROEs, and coupling-constants, along with the limitations imposed by the unique intrinsic characteristics of glycan structure on these approaches: flexibility, range of conformers, signal overlap, and non-first-order scalar (strong) coupling. Novel experiments taking advantage of isotopic labeling are presented as an option for overcoming spectral overlap and raising sensitivity. Computational tools used to explore conformational averaging in conjunction with NMR parameters are described. In addition, recent developments in hydroxyl detection and hydrogen bond detection in protonated solvents, in contrast to traditional sample preparations in D2O for carbohydrates, further increase the tools available for both structure information and chemical shift assignments. We also include previously unpublished data in this context. Accurate determination of couplings in carbohydrates has been historically challenging due to the common presence of strong-couplings. We present new strategies proposed for dealing with their influence on NMR signals. We close with a discussion of residual dipolar couplings (RDCs) and the advantages of using (13)C isotope labeling that allows gathering one-bond (13)C-(13)C couplings with a recently improved constant-time COSY technique, in addition to the commonly measured (1)H-(13)C RDCs.

中文翻译：

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聚糖的 NMR：为旧问题提供新思路

聚糖显示的分子排列和动力学的多样性使得用于蛋白质和核酸的传统 NMR 策略不足。由于聚糖的独特性质，结构研究通常需要采用不同的定制实验和方案。我们介绍了核磁共振技术的最新发展，这将加深我们对聚糖结构-功能关系的理解。我们首先对用于确定蛋白质、核酸和碳水化合物的结构的方法进行调查和比较。接下来，我们讨论从传统 NMR 技术获得的结构信息，如化学位移、NOE/ROE 和偶联常数，以及聚糖结构的独特固有特性对这些方法施加的限制：灵活性、构象异构体的范围、信号重叠和非一阶标量（强）耦合。提出了利用同位素标记的新​​实验，作为克服光谱重叠和提高灵敏度的一种选择。描述了用于结合 NMR 参数探索构象平均的计算工具。此外，与传统的 D2O 中碳水化合物样品制备相比，质子化溶剂中羟基检测和氢键检测的最新发展进一步增加了可用于结构信息和化学位移分配的工具。在这种情况下，我们还包括以前未发表的数据。由于强偶联的普遍存在，准确测定碳水化合物中的偶联历来具有挑战性。我们提出了处理它们对 NMR 信号的影响的新策略。我们最后讨论了残余偶极耦合 (RDC) 以及使用 (13)C 同位素标记的优势，该标记允许使用最近改进的恒定时间 COZY 技术收集单键 (13)C-(13)C 耦合，在除了通常测量的 (1)H-(13)C RDC。