Structural requirements of carbohydrates to bind Agaricus bisporus lectin

• Published in: Glycobiology (Oxford) 1999, Vol.9 (1), p.59-64
• Main Authors: Irazoqui, F.J, Vides, M.A, Nores, G.A
• Format: Article
• Language: English
• Subjects: Agaricus bisporus; Agaricus bisporus lectin; Arachis hypogaea; Binding Sites; Carbohydrate Conformation; Carbohydrate Metabolism; Carbohydrate Sequence; Carbohydrates - chemistry; Chromatography, High Pressure Liquid; Disaccharides - chemistry; Disaccharides - metabolism; Lectins - chemistry; Lectins - metabolism; Models, Molecular; Molecular Sequence Data; Peroxidase - metabolism; plant biochemistry; plant physiology; Structure-Activity Relationship; Thomsen-Friedenreich disaccharide
• ISSN: 0959-6658; 1460-2423
• DOI: 10.1093/glycob/9.1.59

Galβ1–3GalNAc (T-disaccharide) and related molecules were assayed to describe the structural requirements of carbohydrates to bind Agaricus bisporus lectin (ABL). Results provide insight into the most relevant regions of T-disaccharide involved in the binding of ABL. It was found that monosaccharides bind ABL weakly indicating a more extended carbohydrate-binding site as compared to those involved in the T-disaccharide specific lectins such as jacalin and peanut agglutinin. Lacto-N-biose (Galβ1–3GlcNAc) unlike T-disaccharide, is unable to inhibit the ABL interaction, thus showing the great importance of the position of the axial C-4 hydroxyl group of GalNAc in T-disaccharide. This finding could explain the inhibitory ability of Galβ1–6GlcNAc and lactose because C-4 and C-3 hydroxyl groups of reducing Glc, respectively, occupy a similar position as reported by conformational analysis. From the comparison of different glycolipids bearing terminal T-disaccharide bound to different linkages, it can be seen than ABL binding is even more impaired by an adjacent C-6 residual position than by the anomeric influence of T-disaccharide. Furthermore, the addition of β-GlcNAc to the terminal T-disaccharide in C-3 position of Gal does not affect the ABL binding whereas if an anionic group such as glucuronic acid is added to C-3, the binding is partially affected. These findings demonstrate that ABL holds a particular binding nature different from that of other T-disaccharide specific lectins.