Chemoselective Capture of Glycans for Analysis on Gold Nanoparticles: Carbohydrate Oxime Tautomers Provide Functional Recognition by Proteins
Chemoselective Capture of Glycans for Analysis on Gold Nanoparticles: Carbohydrate Oxime Tautomers Provide Functional Recognition by Proteins
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DOI：
10.1002/chem.200801521
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发表时间：
2009-01-01
影响因子：
4.3
通讯作者：
Jensen, Knud J.
中科院分区：
文献类型：
--
作者：
Thygesen, Mikkel B.;Sauer, Jorgen;Jensen, Knud J.
用多聚糖功能化的纳米颗粒正在成为研究蛋白质-碳水化合物相互作用的强大的固相化学工具，利用纳米级的性质来检测结合事件。非常需要能够在两个连续的化学选择性步骤中以有意义的显示多聚糖的方法或试剂从无保护的多聚糖中组装出多聚糖纳米颗粒。在这里，我们描述了一种新型的双功能试剂，它1)通过在溶液中生成肟基与多糖偶联，2)通过亲脂性的三苯基标签帮助纯化，3)脱保护后通过硫醇与金纳米颗粒偶联。核磁共振研究表明，这些肟同时以开链和N-糖基氧胺互变异构体的形式存在。通过置换预先形成的柠檬酸稳定的金纳米颗粒中的配体来偶联Glyean-Linker偶联物。用凝集素刀豆球蛋白A(ConA)、加工酶和糖淀粉酶(GA)研究了凝集素、刀豆蛋白A(ConA)和加工酶(GA)对这些糖链的识别作用。我们证明，N-糖基氧胺的存在明显地使功能识别与相应的还原氧胺形成鲜明对比。这一概念随后在一种新型试剂中实现，这种试剂可以通过操作简单地捕获多糖并展示它们的生物学意义，从而促进纳米糖生物学。
Nanoparticles functionalized with glycans are emerging as powerful solid-phase chemical tools for the study of protein-carbohydrate interactions using nanoscale properties for detection of binding events. Methods or reagents that enable the assembly of glyconanoparticles from unprotected glycans in two consecutive chemoselective steps with meaningful display of the glycan are highly desirable. Here, we describe a novel bifunctional reagent that 1) couples to glycans by oxime formation in solution, 2) aids in purification through a lipophilic trityl tag, and 3) after deprotection then couples to gold nanoparticles through a thiol. NMR studies revealed that these oximes exist as both the open-chain and N-glycosyl oxy-amine tautomers. Glyean-linker conjugates were coupled through displacement of ligands from preformed, citrate-stabilized gold nanoparticles. Recognition of these glycans by proteins was studied with a lectin, concanavalin A (ConA), in an aggregation assay and with a processing enzyme and glucoamylase (GA). We demonstrate that the presence of the N-glycosyl oxy-amines clearly enables functional recognition in sharp contrast to the corresponding reduced oxy-amines. This concept is then realized in a novel reagent, which should facilitate nanoglycobiology by enabling the operationally simple capture of glycans and their biologically meaningful display.