Synthesis and two-dimensional nuclear magnetic resonance analysis of a tetra- and a hexa-saccharide fragment of the O-specific polysaccharide of Shigella dysenteriae type 1.
The synthesis of the tetra- and hexa-saccharide methyl glycosides alpha-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->3)- alpha-L-Rhap- OMe (1), and alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-D-Galp-(1--> 3)-alpha-D-GlcpNAc- (1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-OMe (3) is described, which represent various epitopes of the O-specific polysaccharide of Shigella dysenteriae type 1. The following monosaccharide intermediates were used: 1,3-di-O-acetyl-2-O-benzoyl-4-O-benzyl-alpha-L-rhamnopyranose (6 alpha), methyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside (7), methyl 2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyranoside (8), 2,3,4-tri-O-benzoyl-alpha-L-rhamnopyranosyl bromide (9), methyl 3,4,6-tri-O-benzyl-2-O-(4-methoxybenzyl)-1-thio-beta-D- galactopyranoside (13), methyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D- galactopyranoside (16), and 2-azido-4,6-O-benzylidene-3-O-bromoacetyl-2-deoxy-beta-D- glucopyranosyl chloride (19). A detailed analysis of the 1H and 13C NMR spectra of oligosaccharides 1 and 3 confirmed that the hexasaccharide 3 better approaches the conformation of the native polysaccharide, than either 1 or the homologous pentasaccharide 41.
Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
V
V
Pozsgay
B
B
Coxon
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005690:Galactose; D005944:Glucosamine; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D008961:Models, Structural; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D009904:Optical Rotation; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012210:Rhamnose; D012762:Shigella dysenteriae / Q000737:chemistry* / Q000276:immunology
D007202:Indicators and Reagents; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D005944:Glucosamine; D012210:Rhamnose; D005690:Galactose