Semisynthesis of Intact Complex-Type Triantennary Oligosaccharides from a Biantennary Oligosaccharide Isolated from a Natural Source by Selective Chemical and Enzymatic Glycosylation
Semisynthesis of Intact Complex-Type Triantennary Oligosaccharides from a Biantennary Oligosaccharide Isolated from a Natural Source by Selective Chemical and Enzymatic Glycosylation
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DOI：
10.1021/jacs.5b13098
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发表时间：
2016-03-16
影响因子：
15
通讯作者：
Kajihara, Yasuhiro
中科院分区：
文献类型：
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作者：
Maki, Yuta;Okamoto, Ryo;Kajihara, Yasuhiro
寡糖与蛋白质的附着是主要的翻译后修饰。低聚糖的化学合成有助于阐明这些低聚糖的功能。然而，寡糖连接蛋白的合成仍然具有挑战性，因为它们固有的复杂结构，包括不同的二至四触角形式。我们报告了一种高效的策略，仅通过 9 或 10 步化学转化即可从双触角寡糖获得代表性的两种类型的三触角寡糖，该双触角寡糖可以以异常均质的形式从蛋黄中分离出来。成功地将四个亚苄基缩醛引入到带有24个羟基的双触角脱唾液酸单糖的末端两个半乳糖苷和两个核心甘露糖苷上，然后用乙酰基保护剩余的羟基。选择性去除其中一种亚苄基缩醛得到两种类型的适当保护的糖基受体。用受保护的 Gal-beta-1,4-GlcN 硫代糖苷对各个受体进行糖基化以及随后的去保护步骤成功地产生了两种类型的复合型三触角寡糖。
Attachment of oligosaccharides to proteins is a major post-translational modification. Chemical syntheses of oligosaccharides have contributed to clarifying the functions of these oligosaccharides. However, syntheses of oligosaccharide-linked proteins are still challenging because of their inherent complicated structures, including diverse di- to tetra-antennary forms. We report a highly efficient strategy to access the representative two types of triantennary oligosaccharides through only 9 or 10-step chemical conversions from a biantennary oligosaccharide, which can be isolated in exceptionally homogeneous form from egg yolk. Four benzylidene acetals were successfully introduced to the terminal two galactosides and two core mannosides of the biantennary asialononasaccharide bearing 24 hydroxy groups, followed by protection of the remaining hydroxy groups with acetyl groups. Selective removal of one of the benzylidene acetals gave two types of suitably protected glycosyl acceptors. Glycosylation toward the individual acceptors with protected Gal-beta-1,4-GlcN thioglycoside and subsequent deprotection steps successfully yielded two types of complex-type triantennary oligosaccharides.