Fachbereich Chemie and Konstanz Research School Chemical Biology (KoRS-CB), Universität Konstanz, 78457 Konstanz, Germany.
Beilstein J Org Chem. 2012;8:819-26. doi: 10.3762/bjoc.8.91. Epub 2012 Jun 1.
A series of six mono-, di-, and trivalent N,N'-diacetylchitobiose derivatives was conveniently prepared by employing a one-pot procedure for Cu(II)-catalyzed diazo transfer and Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) starting from commercially available amines. These glycoclusters were probed for their binding potencies to the plant lectin wheat germ agglutinin (WGA) from Triticum vulgaris by an enzyme-linked lectin assay (ELLA) employing covalently immobilized N-acetylglucosamine (GlcNAc) as a reference ligand. IC(50) values were in the low micromolar/high nanomolar range, depending on the linker between the two disaccharides. Binding enhancements β up to 1000 for the divalent ligands and 2800 for a trivalent WGA ligand, compared to N,N'-diacetylchitobiose as the corresponding monovalent ligand, were observed. Molecular modeling studies, in which the chitobiose moieties were fitted into crystallographically determined binding sites of WGA, correlate the binding enhancements of the multivalent ligands with their ability to bind to the protein in a chelating mode. The best WGA ligand is a trivalent cluster with an IC(50) value of 220 nM. Calculated per mol of contained chitobiose, this is the best WGA ligand known so far.
方便地合成了一系列六种单、二价和三价 N,N'-二乙酰壳二糖衍生物，采用一锅法进行铜（II）催化重氮转移和铜（I）催化叠氮-炔环加成（CuAAC），从商业可得的胺起始。通过酶联凝集素测定法（ELLA），用共价固定化 N-乙酰葡萄糖胺（GlcNAc）作为参考配体，研究这些糖簇与植物凝集素麦胚凝集素（WGA）的结合效力。IC50 值在低微摩尔/高纳摩尔范围内，取决于两个二糖之间的连接物。与作为相应单价配体的 N,N'-二乙酰壳二糖相比，二价配体的结合增强β值高达 1000，三价 WGA 配体的结合增强β值高达 2800。分子建模研究表明，壳二糖部分适合 WGA 中结晶确定的结合位点，将多价配体的结合增强与它们以螯合模式结合到蛋白质的能力相关联。最佳的 WGA 配体是三价簇，IC50 值为 220 nM。按所含壳二糖的摩尔计算，这是迄今为止已知的最佳 WGA 配体。
