Wu A M, Wu J H, Song S C, Tsai M S, Herp A
Glyco-Immunochemistry Research Lab, Institute of Molecular and Cellular Biology, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
FEBS Lett. 1998 Dec 4;440(3):315-9. doi: 10.1016/s0014-5793(98)01469-0.
The binding profile of Triticum vulgaris (WGA, wheat germ) agglutinin to 23 O-glycans (GalNAc alpha1-->Ser/Thr containing glycoproteins, GPs) was quantitated by the precipitin assay and its specific interactions with O-glycans were confirmed by the precipitin inhibition assay. Of the 28 glycoforms tested, six complex O-glycans (hog gastric mucins, one human blood group A active and two precursor cyst GPs) reacted strongly with WGA and completely precipitated the lectin added. All of the other human blood group A active O-glycans and human blood group precursor GPs also reacted well with the lectin and precipitated over two-thirds of the agglutinin used. They reacted 4-50 times stronger than N-glycans (asialo-fetuin and asialo-human alpha1 acid GP). The binding of WGA to O-glycans was inhibited by either p-NO2-phenyl alpha,betaGlcNAc or GalNAc. From these results, it is highly possible that cluster (multivalent) effects through the high density of weak inhibitory determinants on glycans, such as GalNAc alpha1-->Ser/Thr (Tn), GalNAc at the nonreducing terminal, GlcNAc beta1--> at the non-reducing end and/or as an internal residue, play important roles in precipitation, while the GlcNAc beta1-->4GlcNAc disaccharide may play a minor role in the precipitation of mammalian glycan-WGA complexes.
通过沉淀素测定法定量分析了普通小麦（WGA，麦胚）凝集素与23种O-聚糖（含GalNAcα1→Ser/Thr的糖蛋白，GPs）之间的结合情况，并通过沉淀素抑制测定法证实了其与O-聚糖的特异性相互作用。在所测试的28种糖型中，六种复合O-聚糖（猪胃粘蛋白、一种人血型A活性和两种前体半胱氨酸GPs）与WGA强烈反应，并使添加的凝集素完全沉淀。所有其他人血型A活性O-聚糖和人血型前体GPs也与凝集素反应良好，并沉淀了超过三分之二的所用凝集素。它们的反应比N-聚糖（去唾液酸胎球蛋白和去唾液酸人α1酸性GP）强4 - 50倍。WGA与O-聚糖的结合可被对硝基苯基α,β-葡萄糖胺或GalNAc抑制。从这些结果来看，很有可能是聚糖上高密度的弱抑制性决定簇（如GalNAcα1→Ser/Thr（Tn）、非还原末端的GalNAc、非还原端的GlcNAcβ1→以及/或者作为内部残基）通过簇集（多价）效应在沉淀过程中发挥重要作用，而GlcNAcβ1→4GlcNAc二糖在哺乳动物聚糖 - WGA复合物的沉淀中可能起次要作用。
