Synthesis, structure, and conformation of the dilactone derivative of GD1b ganglioside.
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.
Fronza
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CNR Study Center for Natural Organic Substances, Department of Chemistry, Polytechnic of Milan, Italy.
Kirschner
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Acquotti
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Sonnino
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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
D005732:Gangliosides; D007783:Lactones; C063923:ganglioside GD1b dilactone