title: On the role of the carboxyl group of sialic acid in binding of cholera toxin to the receptor glycosphingolipid, GM1.
abstract: The carboxyl group of the natural cholera toxin receptor, the ganglioside GM1, Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-Cer, has been converted to a number of C(1)-amides of NeuAc. The binding of cholera toxin B-subunit to these derivatives was monitored by exposing the modified glycolipids, on solid phases, to radiolabeled toxin. Binding was obtained, although substantially reduced, with the amide and to a lesser extent with the benzylamide and also the C(1)-alcohol. In the assay system used, the methyl-, ethyl-, or propylamides did not bind. It was concluded that the hydrogen bonding capacity of a carboxyl or amide group is needed for strong binding. This is in agreement with the recently published crystal structure of the B-subunit in complex with the GM1 pentasaccharide.
authors.affiliation: Department of Medical Biochemistry, Göteborg University, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Lanne
authors.forename: B
authors.initials: B
authors.lastname: Schierbeck
authors.forename: K A
authors.initials: KA
authors.lastname: Karlsson
mesh_terms: D001665:Binding Sites; D002240:Carbohydrate Sequence; D002772:Cholera Toxin / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives* / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012794:Sialic Acids / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D006028:Glycosphingolipids; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D012794:Sialic Acids; C023552:choleragen receptor; C033639:glycolipid receptor; D005677:G(M1) Ganglioside; D002772:Cholera Toxin