Laboratory for Biomaterials, Institute for Biotechnology and Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstraße 20, 52074 Aachen, Germany.
Molecules. 2017 Aug 10;22(8):1320. doi: 10.3390/molecules22081320.
Repeats of the disaccharide unit -acetyllactosamine (LacNAc) occur as type 1 (Galβ1, 3GlcNAc) and type 2 (Galβ1, 4GlcNAc) glycosylation motifs on glycoproteins and glycolipids. The LacNAc motif acts as binding ligand for lectins and is involved in many biological recognition events. To the best of our knowledge, we present, for the first time, the synthesis of LacNAc type 1 oligomers using recombinant β1,3-galactosyltransferase from and β1,3--acetylglucosaminyltranferase from . Tetrasaccharide glycans presenting LacNAc type 1 repeats or LacNAc type 1 at the reducing or non-reducing end, respectively, were conjugated to bovine serum albumin as a protein scaffold by squarate linker chemistry. The resulting multivalent LacNAc type 1 presenting neo-glycoproteins were further studied for specific binding of the tumor-associated human galectin 3 (Gal-3) and its truncated counterpart Gal-3∆ in an enzyme-linked lectin assay (ELLA). We observed a significantly increased affinity of Gal-3∆ towards the multivalent neo-glycoprotein presenting LacNAc type 1 repeating units. This is the first evidence for differences in glycan selectivity of Gal-3∆ and Gal-3 and may be further utilized for tracing Gal-3∆ during tumor progression and therapy.
二糖单元乙酰乳糖胺（LacNAc）的重复出现形式为糖蛋白和糖脂上的 1 型（Galβ1,3GlcNAc）和 2 型（Galβ1,4GlcNAc）糖基化模式。LacNAc 基序作为凝集素的结合配体，参与许多生物识别事件。据我们所知，我们首次使用 重组的β1,3-半乳糖基转移酶和β1,3-N-乙酰氨基葡萄糖基转移酶从 合成了 LacNAc 1 型低聚物。分别在还原或非还原端呈现 LacNAc 1 型重复或 LacNAc 1 型的四糖聚糖通过 squarate 接头化学连接到牛血清白蛋白作为蛋白质支架上。所得的具有多价 LacNAc 1 型的新型糖蛋白进一步研究了其与肿瘤相关的人半乳糖凝集素 3（Gal-3）及其截断对应物 Gal-3∆在酶联凝集素测定（ELLA）中的特异性结合。我们观察到 Gal-3∆对具有多价 LacNAc 1 重复单元的新型糖蛋白的亲和力显著增加。这是 Gal-3∆和 Gal-3 在聚糖选择性上存在差异的第一个证据，并且可以进一步用于在肿瘤进展和治疗过程中追踪 Gal-3∆。
