Synthesis and conformational studies of the tyvelose capped, Lewis-x like tetrasaccharide epitope of Trichinella spiralis.
Synthesis and conformational studies of the tyvelose capped, Lewis-x like tetrasaccharide epitope of Trichinella spiralis.
复制标题
旋毛虫的 tyverose 封端的 Lewis-x 样四糖表位的合成和构象研究。
DOI：
10.1016/s0968-0896(96)00182-4
复制
发表时间：
1996
影响因子：
3.5
通讯作者：
Bundle,DR
中科院分区：
文献类型：
--
作者：
Zhang,J;Otter,A;Bundle,DR
报道了作为旋毛虫细胞表面聚糖末端元件的四糖表位和组成结构的化学合成和高分辨率核磁共振研究。采用硫代糖苷和卤离子糖基化方法从单糖合成子中合成了Lewis-x型三糖的2-(三甲基甲硅烷基)乙基和甲基糖苷，其中βGalNAc取代了βGal。利用不溶性银沸石催化剂和糖基卤化物，将独特的 3,6-二脱氧-β-d-阿拉伯吡喃糖基残基引入到选择性保护的 2-（三甲基甲硅烷基）乙基和甲基三糖苷中。在单独的反应中，不仅获得了主要目标，还获得了相应的 α-连接四糖。甲基四糖苷的 NMR 谱比较表明，在 α-连接的 tyverose 结构位点，特定的 GalNAc 共振（C-1、C-2、C-3）具有异常宽的 13 C (8–21 Hz) 和 1 H 谱线。代表天然寄生虫表位的β-连接四糖苷仅表现出窄线宽（3 Hz，13C）。由于 NOE 得出的 α-连接 tyverose 结构的距离限制与不寻常的糖苷构象异构体的存在不一致，因此有限数量的宽线的起源归因于 GalNAc 残基中 Tyvelose 糖基化位点的局部刚性。
Chemical synthesis and high resolution NMR studies are reported for the tetrasaccharide epitope and constituent structures that occur as terminal elements of Trichinella spiralis cell surface glycans. The 2-(trimethylsilyl)ethyl and methyl glycosides of Lewis-x type trisaccharides, in which βGalNAc replaces βGal were synthesized from monosaccharide synthons utilizing thioglycoside and halide-ion glycosylation methods. The unique 3,6-dideoxy-β-d-arabinohexopyranosyl residue that caps the structure was introduced to selectively protected 2-(trimethylsilyl)ethyl and methyl trisaccharide glycosides by utilizing an insoluble silver zeolite catalyst and a glycosyl halide. In separate reactions not only were the principal targets obtained but also the corresponding α-linked tetrasaccharides. A comparison of the NMR spectra of the methyl tetrasaccharide glycosides showed that at the site of the α-linked tyvelose structure, specific GalNAc resonances (C-1, C-2, C-3) possess uncharacteristically wide13C (8–21 Hz) and1H lines. The β-linked tetrasaccharide glycoside, that represents the native parasite epitope, exhibited only narrow line widths (3 Hz,13C). Since NOE derived distance constraints for the α-linked tyvelose structure were not consistent with the existence of unusual glycosidic conformers, the origin of the limited number of wide lines was attributed to local rigidity in the GalNAc residue, at the site of tyvelose glycosylation.