2-Oxabutane as a substitute for internal monomer units of oligosaccharides to create lectin ligands
作者:Li-Ying Yang、Yuki Kawada、Lina Bai、Daijiro Kubota、Hideya Yuasa
DOI:10.1039/c1ob05775h
日期:——
The synthesis of bioactive oligosaccharides is too tedious to scale up for commercialization. However, structurally simplified glycomimetics are commercializable, if they can be synthesized much more easily than the oligosaccharides while having a comparable bioactivity. In this study, we propose a 2-oxabutane (OB) structure as an imitation of the internal monosaccharide units in oligosaccharides. Two trimannoside and three pentamannoside OB-glycomimics were synthesized in remarkably short steps. Among them, Manα1-OB-2Man 10, a trimannoside mimic, showed eight-fold affinity toward concanavalin A (ConA) relative to methyl mannoside in latex agglutination lectin assay and equilibrium dialysis assay (EDA), while the other mimics showed three- to four-fold affinities. EDA indicated that the bindings between each mimic molecule and a ConA subsite were all in one-to-one stoichiometry and thus these mimics were monovalent ligands, excluding multivalence effect for the high affinities. The strong affinity of 10 could be explained by the occupation of two mannose binding sites of a ConA subsite by its two mannose units. Mimic 10 proved to be even a better ligand for ConA than the natural disaccharide Manα1,2Man, while been much more easy to synthesize, thereby illustrating the potential of the approach here presented.
生物活性低聚糖的合成过于繁琐,无法扩大商业化规模。然而,如果结构简化的拟糖类化合物能比低聚糖更容易合成,同时又具有相当的生物活性,那么它们是可以商业化的。在这项研究中,我们提出了一种 2-氧杂丁烷(OB)结构,作为低聚糖内部单糖单元的仿生结构。我们在极短的时间内合成了两种三单糖苷和三种五单糖苷的 OB-甘聚物。其中,Manα1-OB-2Man 10 是一种三单糖苷模拟物,在胶乳凝集凝集素试验和平衡透析试验(EDA)中,它对 concanavalin A(ConA)的亲和力是甲基甘露糖苷的八倍,而其他模拟物的亲和力为三至四倍。EDA 表明,每个模拟物分子与一个 ConA 亚位点之间的结合都是一一对应的,因此这些模拟物是单价配体,排除了高亲和力的多价效应。10 的强亲和力可解释为其两个甘露糖单位占据了 ConA 位点的两个甘露糖结合位点。事实证明,与天然二糖 Manα1,2Man 相比,模拟 10 甚至是更好的 ConA 配体,而且更容易合成,从而说明了本文所介绍方法的潜力。