title: Synthesis and NMR assignment of two repeating units (decasaccharide) of the type III group B Streptococcus capsular polysaccharide and its 13C-labeled and N-propionyl substituted sialic acid analogues.
abstract: For the purpose of carrying out a comprehensive investigation into the nature of the conformational epitope of the type III group B Streptococcus polysaccharide, combined chemical and enzymatic methods were applied to the synthesis of three decasaccharide probes, namely beta-D-Glc-(1-->6)[alpha-NeuR-(2-->3)-beta-D-Gal-(1-->4)] -beta-D-GlcNAc-(1-->3)-beta-D-Gal-(1-->4)-beta-D- Glc-(1-->6)[alpha-NeuR-(2-->3)-beta-D-Gal-(1-->4)]-beta-D-GlcNAc-( 1-->3) -beta-D-Gal-OMe (22 NeuR = NeuAc; 23 NeuR = NeuAc with 8% 13C-labeling; 24 NeuR = NeuPr). The precursor core octasaccharide 21 was chemically synthesized from trisaccharide donor 11 and pentasaccharide acceptor 19 by block condensation. Sialylation of 21 with alpha-(2-->3)-sialyltransferase and CMP-NeuAc afforded 22. In the presence of CMP-sialic acid synthetase and alpha-(2-->3)-sialyltransferase, 21 was sialylated with sialic acid derivatives (8% 13C-labeled, or N-propionyl substituted) to give 23 and 24, respectively. Complete assignments of the 1H and 13C NMR spectra of compounds 21, 22 (23), and 24 are also presented.
authors.affiliation: Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Zou
authors.forename: J R
authors.initials: JR
authors.lastname: Brisson
authors.forename: Q L
authors.initials: QL
authors.lastname: Yang
authors.forename: M
authors.initials: M
authors.lastname: van der Zwan
authors.forename: H J
authors.initials: HJ
authors.lastname: Jennings
mesh_terms: D016667:Bacterial Capsules / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000031:analogs & derivatives / Q000737:chemistry*; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D011135:Polysaccharides, Bacterial; D011422:Propionates / Q000737:chemistry; D012091:Repetitive Sequences, Nucleic Acid; D013292:Streptococcus agalactiae / Q000737:chemistry*
chemical_list: D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D011422:Propionates; D019158:N-Acetylneuraminic Acid