title: Synthesis, structure, and conformation of the dilactone derivative of GD1b ganglioside.
abstract: Treatment of DG1b, beta-Gal-(1----3)-beta-GalNAc-(1---- 4)-[alpha-Neu5Ac-(2----8)-alpha-Neu5Ac-(2---- 3)]-beta-Gal-(1----4)-beta-Glc-(1----1)-Cer, with dicyclohexylcarbodi-imide in anhydrous methyl sulfoxide affords 95-98% of GD1b-dilactone. The carboxyl groups of the two sialic acid units are involved in ester linkages, as proved by ammoniolysis and reduction which gave derivatives containing the amide of sialic acid and N-acetylneuraminulose, respectively. 1H-N.m.r. spectroscopy showed that the lactone rings involved position 9 of the inner sialic acid and position 2 of the inner galactose and that the disialosyl chain is extended toward the -beta-Gal-(1 ----4)-beta-Glc- portion of the ganglioside moiety.
authors.affiliation: CNR Study Center for Natural Organic Substances, Department of Chemistry, Polytechnic of Milan, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Fronza
authors.forename: G
authors.initials: G
authors.lastname: Kirschner
authors.forename: D
authors.initials: D
authors.lastname: Acquotti
authors.forename: S
authors.initials: S
authors.lastname: Sonnino
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002855:Chromatography, Thin Layer; D003124:Colorimetry; D003720:Densitometry; D005732:Gangliosides / Q000138:chemical synthesis; D007783:Lactones / Q000138:chemical synthesis; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data
chemical_list: D005732:Gangliosides; D007783:Lactones; C063923:ganglioside GD1b dilactone