Bi- to tetravalent glycoclusters: synthesis, structure–activity profiles as lectin inhibitors and impact of combining both valency and headgroup tailoring on selectivity
作者:Guan-Nan Wang、Sabine André、Hans-Joachim Gabius、Paul V. Murphy
DOI:10.1039/c2ob25870f
日期:——
The emerging functional versatility of cellular glycans makes research on the design of synthetic inhibitors a timely topic. In detail, the combination of ligand (or headgroup or contact site) structure with spatial parameters that depend on topological and geometrical factors underlies the physiological selectivity of glycan-protein (lectin) recognition. We herein tested a panel of bi-, tri- and tetravalent compounds against two plant agglutinins and adhesion/growth-regulatory lectins (galectins). In addition, we examined the impact of headgroup tailoring (converting lactose to 2â²-fucosyllactose) in combination with valency increase in two assay types of increasing biorelevance (from solid-phase binding to cell binding). Compounds were prepared using copper-catalysed azide alkyne cycloaddition from peracetylated lactosyl or 2â²-fucosyllactosyl azides. Significant inhibition was achieved for the plant toxin with a tetravalent compound. Different levels of sensitivity were noted for the three groups of the galectin family. The headgroup extension to 2â²-fucosyllactose led to a selectivity gain, especially for the chimera-type galectin-3. Valency increase established discrimination against the homodimeric proteins, whereas the combination of valency with the headgroup extension led to discrimination against the tandem-repeat-type galectin-8 for chicken galectins but not human galectins-3 and -4. Thus, detailed structureâactivity profiling of glycoclusters combined with suitably modifying the contact site for the targeted lectin will help minimize cross-reactivity among this class of closely related proteins.
细胞糖类日益显现的功能多样性使得合成抑制剂设计的研究成为一个及时的话题。具体而言,配体(或头基或接触位点)结构与依赖于拓扑和几何因素的空间参数的结合构成了糖类-蛋白质(凝集素)识别的生理选择性。本文测试了一系列二价、三价和四价化合物,以针对两种植物凝集素和粘附/生长调节凝集素(伽星素)。此外,我们还研究了头基调节(将乳糖转化为2'-呋喃乳糖)与在两个生物相关性的测定类型中增加价态的结合影响(从固相结合到细胞结合)。化合物通过铜催化的叠氮炔烃环加成反应,从过乙酰化的乳糖基或2'-呋喃乳糖基叠氮化物制备而成。使用四价化合物对植物毒素实现了显著的抑制。伽星素家族的三个组别表现出不同程度的敏感性。将头基延伸至2'-呋喃乳糖带来了选择性增强,特别是对于混合型伽星素-3。增加价态在区分同源二聚体蛋白方面表现出作用,而将价态与头基延伸结合则导致对鸡伽星素的串联重复型伽星素-8的区分,但对人类伽星素-3和-4则没有影响。因此,详细的糖簇结构-活性谱分析结合适当地调节目标凝集素的接触位点,将有助于最小化这一类密切相关蛋白之间的交叉反应性。