Abstract：
Solution nuclear magnetic resonance (NMR) analysis of polysaccharides can provide valuable information not only on their primary structures but also on their conformation, dynamics, and interactions under physiological conditions. One of the main problems is that non-anomeric 1H signals typically overlap, and this often hinders detailed NMR analysis. Isotope enrichment, such as with 13C and 15N, will add a new dimension to the NMR spectra of polysaccharides, and spectral analysis can be performed with enhanced sensitivity using isolated peaks. For this purpose, here we have prepared uniformly 13C- and/or 15N-labeled chondroitin polysaccharides -4)-β-D-glucuronopyranosyl-(1-3)-2-acetamido-2-deoxy-β-D-galactopyranosyl-(1- with molecular weights in the range from 310 to 460 k by bacterial fermentation. The enrichment ratios for 13C and 15N were 98.9 and 99.8%, respectively, based on the mass spectrometric analysis of the constituent chondroitin disaccharides. 1H and 13C NMR signals were assigned mainly based on HSQC and 13C-detection experiments including INADEQUATE, HETCOR, and HETCOR-TOCSY. The carbonyl carbon signal of the N-acetyl-β-D-galactosamine residue was unambiguously distinguished from the C6 carbon of the β-D-glucuronic acid residue by the observation of 13C peak splitting due to 1JCN coupling in 13C- and 15N-labeled chondroitin. The T2* and T1 were measured and indicate that both rigid and mobile sites are present in the long sequence of chondroitin. The conformation, dynamics, and interactions of chondroitin and its derivatives will be further analyzed based on the results obtained in this study.
摘要：
多糖的溶液核磁共振（NMR）分析不仅可以提供有关其一级结构的有价值的信息，而且可以提供有关其构象的信息。动力学,和生理条件下的相互作用。其中一个主要问题是，非端基1H信号通常重叠，这往往会阻碍详细的核磁共振分析。同位素富集，例如13C和15N，将为多糖的核磁共振谱增加一个新的维度，和光谱分析可以使用分离的峰以增强的灵敏度进行。为此,在这里，我们均匀地制备了13个C-和/或15个N-标记的软骨素多糖-4）-β-D-葡萄糖醛酸吡喃-（1-3）-2-乙酰氨基-2-脱氧-β-D-吡喃半乳糖-（1-通过细菌发酵，分子量范围为310至460k。13C和15N的富集率分别为98.9%和99.8%,分别,基于成分软骨素二糖的质谱分析。1H和13CNMR信号主要基于HSQC和13C检测实验，包括INADEQUATE，HETCOR,还有Hetcor-Tocsy.N-乙酰基-β-D-半乳糖胺残基的羰基碳信号与β-D-葡萄糖醛酸残基的C6碳明确区分开来，通过观察13C和15N-标记的软骨素中1个JCN偶联导致的13C峰分裂。测量了T2*和T1，表明软骨素的长序列中存在刚性和移动位点。构象，动力学,以及软骨素及其衍生物的相互作用将根据本研究获得的结果进行进一步分析。
