title: Thermodynamic, kinetic, and electron microscopy studies of concanavalin A and Dioclea grandiflora lectin cross-linked with synthetic divalent carbohydrates.
abstract: The jack bean lectin concanavalin A (ConA) and the Dioclea grandiflora lectin (DGL) are highly homologous Man/Glc-specific members of the Diocleinae subtribe. Both lectins bind, cross-link, and precipitate with carbohydrates possessing multiple terminal nonreducing Man residues. The present study investigates the binding and cross-linking interactions of ConA and DGL with a series of synthetic divalent carbohydrates that possess spacer groups with increasing flexibility and length between terminal alpha-mannopyranoside residues. Isothermal titration microcalorimetry was used to determine the thermodynamics of binding of the two lectins to the divalent analogs, and kinetic light scattering and electron microscopy studies were used to characterize the cross-linking interactions of the lectins with the carbohydrates. The results demonstrated that divalent analogs with flexible spacer groups between the two terminal Man residues possess higher affinities for the two lectins as compared with those with inflexible spacer groups. Furthermore, despite their high degree of homology, ConA and DGL exhibit differences in their kinetics of cross-linking and precipitation with the divalent analogs. Electron microscopy shows the loss of organized cross-linked lattices of the two lectins with analogs possessing increased distance between the terminal Man residues. The loss of lattice patterns with the analogs is distinct for each lectin. These results have important implications for the interactions of lectins with multivalent carbohydrate receptors in biological systems.
authors.affiliation: Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: Tarun K
authors.initials: TK
authors.lastname: Dam
authors.forename: Stefan
authors.initials: S
authors.lastname: Oscarson
authors.forename: René
authors.initials: R
authors.lastname: Roy
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Das
authors.forename: Daniel
authors.initials: D
authors.lastname: Pagé
authors.forename: Frank
authors.initials: F
authors.lastname: Macaluso
authors.forename: C Fred
authors.initials: CF
authors.lastname: Brewer
mesh_terms: D002151:Calorimetry; D003208:Concanavalin A / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D008362:Mannosides / Q000737:chemistry* / Q000378:metabolism; D037121:Plant Lectins / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
chemical_list: C043014:Dioclea grandiflora lectin; D008362:Mannosides; D037121:Plant Lectins; D003208:Concanavalin A