André Sabine, Kaltner Herbert, Furuike Tetsuya, Nishimura Shin-Ichiro, Gabius Hans-Joachim
Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, Veterinärstr. 13, D-80539 Munich, Germany.
Bioconjug Chem. 2004 Jan-Feb;15(1):87-98. doi: 10.1021/bc0340666.
Multivalent glycoclusters have the potential to become pharmaceuticals by virtue of their target specificity toward clinically relevant sugar receptors. Their application can also provide fundamental insights into the impact of two spatial factors on binding, i.e., topologies of ligand (branching mode, cluster presentation) and carbohydrate recognition domains in lectins. Persubstituted macrocycles derived from nucleophilic substitution of iodide from heptakis 6-deoxy-6-iodo-beta-cyclodextrin by the unprotected sodium thiolate of 3-(3-thioacetyl propionamido)propyl glycosides (galactose, lactose and N-acetyllactosamine) were prepared. The produced glycoclusters were first tested as competitive inhibitors in solid-phase assays. A plant toxin from mistletoe and an immunoglobulin G fraction from human serum were markedly susceptible. A nearly 400-fold increase in inhibitory potency of each galactose moiety in the heptavalent form relative to free lactose (217-fold relative to free galactose) was detected. Thus, these glycoclusters can efficiently interfere, for example, with xenoantigen-dependent hyperacute rejection. Among the tested galectins selected from this family of adhesion- and growth-regulatory endogenous lectins, the substituted beta-cyclodextrins acted as sensors to delineate topological differences between the two dimeric prototype proteins. The relatively strong reactivity with chimera-type galectin-3, a mediator of tumor metastasis, disclosed selectivity for glycocluster binding among galectins. Equally important, the geometry of ligand display (maxiclusters, bi- or triantennary N-glycans) made its mark on the inhibitory potency. To further determine the sensitivity of a distinct galectin presented on the cell surface and not in solution, we established a stably transfected tumor cell clone. We detected a significant response to presence of the multivalent inhibitor. This type of chemical scaffold with favorable pharmacologic properties might thus be exploited for the design of galectin- and ligand-type-selective glycoclusters.
多价糖簇凭借其对临床相关糖受体的靶向特异性，有潜力成为药物。它们的应用还能为两个空间因素对结合的影响提供基本见解，即配体的拓扑结构（分支模式、簇呈现）和凝集素中的碳水化合物识别结构域。通过用3-(3-硫代乙酰丙酰胺基)丙基糖苷（半乳糖、乳糖和N-乙酰乳糖胺）的未保护硫醇钠对七(6-脱氧-6-碘-β-环糊精)进行亲核取代碘化物，制备了衍生的全取代大环化合物。所制备的糖簇首先在固相分析中作为竞争性抑制剂进行测试。来自槲寄生的植物毒素和人血清中的免疫球蛋白G组分对其明显敏感。检测到七价形式的每个半乳糖部分的抑制效力相对于游离乳糖增加了近400倍（相对于游离半乳糖增加了217倍）。因此，这些糖簇可以有效地干扰，例如，异种抗原依赖性超急性排斥反应。在从这个粘附和生长调节内源性凝集素家族中选择的测试半乳糖凝集素中，取代的β-环糊精作为传感器来描绘两种二聚体原型蛋白之间的拓扑差异。与肿瘤转移介质嵌合型半乳糖凝集素-3的相对较强反应性，揭示了半乳糖凝集素之间糖簇结合的选择性。同样重要的是，配体展示的几何形状（最大簇、双天线或三天线N-聚糖）对抑制效力产生了影响。为了进一步确定存在于细胞表面而非溶液中的特定半乳糖凝集素的敏感性，我们建立了一个稳定转染的肿瘤细胞克隆。我们检测到对多价抑制剂的存在有显著反应。因此，这种具有良好药理特性的化学支架可用于设计半乳糖凝集素和配体类型选择性的糖簇。
