NMR characterization of endogenously O-acetylated oligosaccharides isolated from tomato (Lycopersicon esculentum) xyloglucan
NMR characterization of endogenously O-acetylated oligosaccharides isolated from tomato (Lycopersicon esculentum) xyloglucan
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DOI：
10.1016/j.carres.2005.04.015
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发表时间：
2005-08-15
影响因子：
3.1
通讯作者：
York, WS
中科院分区：
文献类型：
--
作者：
Jia, ZH;Cash, M;York, WS
从悬浮培养番茄细胞的培养滤液中分离得到植物多糖木糖葡聚糖，经内切葡聚糖酶处理后生成8个低聚糖亚基，并用核磁共振波谱技术对其进行了结构表征。这些低聚糖含有多达三个内源性的o -乙酰基取代基，由一个纤维素四糖核心组成，在核心的非还原末端的两个β - d - glcp残基的O-6处有α - d - xyylp残基。一些- d - xylp残基本身在O-2上有- l - arap或- d - galp残基。o -乙酰基取代基位于未支链（内部）β - d - glcp残基的O-6位，末端β - d - galp残基的O-6位和末端α - l - arap残基的O-5位。在高分辨率gCOSY光谱中观察到的远程标量耦合相互作用促进了结构赋值。gCOSY光谱中存在的五键标量偶联常数提供了一种分配o -乙酰化位点的直接方法，这可能在o -乙酰化聚糖的分析中普遍有用。这些内源性o -乙酰化寡糖的光谱分配使得推断其结构特征与核磁共振诊断共振的化学位移之间的相关性成为可能。(c) 2005年Elsevier Ltd出版
Eight oligosaccharide subunits, generated by endoglucanase treatment of the plant polysaccharide xyloglucan isolated from the culture filtrate of suspension-cultured tomato (Lycopersicon esculentum) cells, were structurally characterized by NMR spectroscopy. These oligosaccharides, which contain up to three endogenous O-acetyl substituents, consist of a cellotetraose core with alpha-D-Xylp residues at O-6 of the two beta-D-Glcp residues at the non-reducing end of the core. Some of the alpha-D-Xylp residues themselves bear either an alpha-L-Arap or a beta-D-Galp residue at O-2. O-Acetyl substituents are located at O-6 of the unbranched (internal) beta-D-Glcp residue, O-6 of the terminal beta-D-Galp residue, and/or at O-5 of the terminal alpha-L-Arap residue. Structural assignments were facilitated by long-range scalar coupling interactions observed in the high-resolution gCOSY spectra of the oligosaccharides. The presence of five-bond scalar coupling constants in the gCOSY spectra provides a direct method of assigning O-acetylation sites, which may prove generally useful in the analysis of O-acylated glycans. Spectral assignment of these endogenously O-acetylated oligosaccharides makes it possible to deduce correlations between their structural features and the chemical shifts of diagnostic resonances in their NMR spectra. (c) 2005 Published by Elsevier Ltd.