title: Total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha: a high affinity ligand for myelin-associated glycoprotein (MAG).
abstract: An efficient total synthesis of a cholinergic neuron-specific ganglioside GT1a alpha (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4Cer) is described. The suitably protected sialyl-alpha(2-->6)-gangliotriose (III6NeuAc-GgOse3) derivative was glycosylated with the phenyl 2-thioglycoside of sialic acid in the presence of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethane-sulfonate (TMSOTf) in acetonitrile medium, giving the disialogangliotriose (III6NeuAcII3NeuAc-GgOse3) derivative which contains both sialyl-alpha(2-->6)-GalNAc and sialyl-alpha(2-->3)-Gal structures (Route I). This pentasaccharide was efficiently synthesized also by the coupling of (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->6)-2-deoxy-3,4-O-isopropylidene-2-ph thalimido-D-galactopyranosyl trichloroacetimidate with 2-(trimethylsilyl)ethyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2-nonulopyranosylonate)-(2-->3)-(2,6-di-O-benzyl-beta-D-galactopy ranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, followed by conversion of the phthalimido group to the acetamido group (Route II). O-Deisopropylidenation and further glycosylation with methyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-gala ct-2-nonulopyranosylonate)-(2-->3)-2,4,6-tri-O-benzoyl-1-thio-b eta-D-galactopyranoside, promoted by dimethyl(methylthio)sulfonium triflate (DMTST), gave the desired trisialogangliotetraose (IV3NeuAcIII6NeuAcII3NeuAc-GgOse4) derivative, which was converted stepwise into the title ganglioside GT1a alpha by the introduction of the ceramide part and then complete deprotection. The ganglioside obtained was shown to be identical with the native GT1a alpha on TLC-immunostaining.
authors.affiliation: Department of Applied Bioorganic Chemistry, Gifu University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: H
authors.initials: H
authors.lastname: Ishida
authors.forename: H
authors.initials: H
authors.lastname: Waki
authors.forename: S
authors.initials: S
authors.lastname: Ando
authors.forename: M
authors.initials: M
authors.lastname: Kiso
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000737:chemistry; D002518:Ceramides / Q000378:metabolism; D002799:Cholinergic Fibers / Q000737:chemistry*; D002855:Chromatography, Thin Layer; D005732:Gangliosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D018992:Myelin-Associated Glycoprotein / Q000378:metabolism*; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009474:Neurons / Q000737:chemistry*; D009844:Oligosaccharides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding
chemical_list: D002518:Ceramides; D005732:Gangliosides; D008024:Ligands; D018992:Myelin-Associated Glycoprotein; D009844:Oligosaccharides; C084318:GT1aalpha ganglioside; D019158:N-Acetylneuraminic Acid