Conformation analysis of D-glucaric acid in deuterium oxide by NMR based on its JHH and JCH coupling constants
Conformation analysis of D-glucaric acid in deuterium oxide by NMR based on its JHH and JCH coupling constants
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基于 JHH 和 JCH 耦合常数的 NMR 分析氧化氘中的 D-葡萄糖二酸构象
DOI：
10.1002/mrc.4396
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发表时间：
2016
影响因子：
2
通讯作者：
Kazuo Furihata and Tadahisa Iwata
中科院分区：
文献类型：
--
作者：
Yukiko Enomoto-Rogers;Hisaharu Masaki;Tetsuya Ito;Kazuo Furihata and Tadahisa Iwata
d‐Glucaric acid （GA）是一种醛酸，由不对称的无环糖主链和位于其结构两端的羧基（即C1和C6位置）组成。本研究的目的是利用质子-质子（3JHH）和质子-碳（2JCHand3JCH）耦合常数以及核overhauser效应光谱（NOESY），基于j -分辨构象分析，利用核磁共振波谱法对柔性GA作为氧化氘溶液进行构象分析。采用j -分辨异核多键相关（HMBC） NMR技术测量了2jchand3jch偶联常数。NOESY相关实验表明，H2和H5的距离很近，尽管这些质子在完全伸展的链结构中相隔太远，无法提供NOESY相关。根据j -耦合值和NOESY相关性，依次评估了沿三个不同键（即C2 - C3， C3 - C4和C4 - C5）的三种可能的构象的有效性。分析结果表明，GA有三种主要的构象，其中构象1为H2H3：间扭式、H3H4：反式和H4H5：间扭式；构象2为H2H3：间扭式，H3H4：反式，H4H5：反式；构象3为H2H3：间扭式，H3H4：间扭式，H4H5：反式。这些结果还表明，这三种构象相互平衡存在。最后，目前的研究结果表明，GA在溶液中的构象结构是弯曲的，而不是完全扩展的。版权所有©2016 John Wiley & Sons， Ltd。
d‐Glucaric acid (GA) is an aldaric acid and consists of an asymmetric acyclic sugar backbone with a carboxyl group positioned at either end of its structure (i.e., the C1 and C6 positions). The purpose of this study was to conduct a conformation analysis of flexible GA as a solution in deuterium oxide by NMR spectroscopy, based onJ‐resolved conformation analysis using proton–proton (3JHH) and proton–carbon (2JCHand3JCH) coupling constants, as well as nuclear overhauser effect spectroscopy (NOESY). The2JCHand3JCHcoupling constants were measured using theJ‐resolved heteronuclear multiple bond correlation (HMBC) NMR technique. NOESY correlation experiments indicated that H2 and H5 were in close proximity, despite the fact that these protons were separated by too large distance in the fully extended form of the chain structure to provide a NOESY correlation. The validities of the three possible conformers along the three different bonds (i.e., C2C3, C3C4, and C4C5) were evaluated sequentially based on theJ‐coupling values and the NOESY correlations. The results of these analyses suggested that there were three dominant conformers of GA, including conformer1, which was H2H3:gauche, H3H4:anti, and H4H5:gauche; conformer2, which was H2H3:gauche, H3H4:anti, and H4H5:anti; and conformer3, which was H2H3:gauche, H3H4: gauche, and H4H5:anti. These results also suggested that all three of these conformers exist in equilibrium with each other. Lastly, the results of the current study suggested that the conformational structures of GA in solution were ‘bent’ rather than being fully extended. Copyright © 2016 John Wiley & Sons, Ltd.