Further characterization of the saccharide specificity of peanut (Arachis hypogaea) agglutinin

Abstract

2-Dansylamino-2-deoxy-d-galactose (GalNDns) has been shown to bind to peanut (Arachis hypogaea) agglutinin (PNA) in a saccharide-specific manner. This binding was accompanied by a five-fold increase in the fluorescence of GalNDns. The interaction was characterized by an association constant of 0.15 mm at 15° and ΔH and ΔS values of - 57.04kJ·mol-1 and - 118.1J·mol-1·K-1, respectively. Binding of a variety of other mono-, di- and oligo-saccharides to PNA, studied by monitoring their ability to dissociate the PNA-GalNDns complex, revealed that PNA interacts with several T-antigen-related structures, such as β-d-Galp-(1→3)-d-GalNAc, β-d-Galp-(1→3)-α-d-GalpNAcOMe, and β-d-Galp-(1→3)-α-d-GalpNAc-(1→3)-Ser, as well as the asialo-GM1 tetrasaccharide, with comparable affiity, thus showing that this lectin does not discriminate between saccharides in which the penultimate sugar of the β-d-Galp-(1→3)-d-GalNAc unit is the α or β anomer, in contrast to jacalin (Artocarpus integrifolia agglutinin), another anti T-lectin which preferentially binds to β-d-Galp-(1→3)-α-d-GalNAc and does not recognize β-d-Galp-(1→3)-β-d-GalNAc or the related asialo-GM1 oligosaccharide. These studies also indicated that, in the extended combining region of PNA which accommodates a disaccharide, the primary subsite (subsite A) is highly specific for d-galactose, whereas the secondary subsite (subsite B) is less specific and can accommodate various structures, such as d-galactose, 2-acetamido-2-deoxy-d-galactose, d-glucose, and 2-acetamido-2-deoxy-d-glucose. © 1991.