Polyvalency of Tn (GalNAcalpha1-->Ser/Thr) glycotope as a critical factor for Vicia villosa B4 and glycoprotein interactions.
Vicia villosa B(4) (VVL-B(4)) is an important lectin for detecting exposed Tn (GalNAcalpha1-Ser/Thr) determinants on cancer cells. In order to elucidate the binding factors involved in VVL-B(4) 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-B(4) binding is polyvalency at the alpha anomer of Gal with -NH CH(3)CO at carbon-2 (Tn epitope), which enhances the reactivity by 3.3x10(5) times over monovalent Gal. The reactivities of glycotopes can be ranked as follows: high density Tn cluster >>Tn glycopeptides (MW<3.0x10(3) >> monomeric Tn to tri- Tn glycopeptides >>> other GalNAcalpha/beta-related structural units>Gal and Galalpha- or beta-linked ligands, demonstrating the essential role of the polyvalency of Tn glycotopes in the enhancement of the binding.
Wu
Albert M
AM
Glyco-Immunochemistry Research Laboratory, Institute of Molecular and Cellular Biology, College of Medicine, Chang-Gung University, Kwei-San, Tao-Yuan 333, Taiwan. amwu@mail.cgu.edu.tw
D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D019158:N-Acetylneuraminic Acid / Q000737:chemistry / Q000378:metabolism; D009369:Neoplasms / Q000737:chemistry / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D037121:Plant Lectins / Q000737:chemistry / Q000378:metabolism*; D031306:Vicia / Q000737:chemistry*
D015295:Antigens, Tumor-Associated, Carbohydrate; D006023:Glycoproteins; D009844:Oligosaccharides; D037121:Plant Lectins; C040286:Tn antigen; D019158:N-Acetylneuraminic Acid