Polyvalency of Tn (GalNAcα1→Ser/Thr) glycotope as a critical factor for Vicia villosa B4 and glycoprotein interactions

摘要

> Vicia villosa B₄ (VVL-B₄) is an important lectin for detecting exposed Tn (GalNAcα1-Ser/Thr) determinants on cancer cells. In order to elucidate the binding factors involved in VVL-B₄ and glycotope interaction, the binding properties of this lectin were analyzed by enzyme-linked lectinosorbent and inhibition assays. From the results, it is concluded that the most critical factor affecting VVL-B₄ binding is polyvalency at the α anomer of Gal with –NH CH₃CO at carbon-2 (Tn epitope), which enhances the reactivity by 3.3×105 times over monovalent Gal. The reactivities of glycotopes can be ranked as follows: high density Tn cluster≫Tn glycopeptides (MW3.0×103)≫monomeric Tn to tri- Tn glycopeptides⋙other GalNAcα/β-related structural unitsGal and Galα- or β-linked ligands, demonstrating the essential role of the polyvalency of Tn glycotopes in the enhancement of the binding.