title: Structural elucidation of two capsular polysaccharides from one strain of Bacteroides fragilis using high-resolution NMR spectroscopy.
abstract: The capsule of Bacteroides fragilis is unusual in that it consists of two distinct capsular polysaccharides. Using a combination of high-resolution NMR spectroscopy, theoretical calculations, and as few chemical procedures as required, the structure of both polysaccharide antigens (polysaccharides A and B) was elucidated. Using the above procedures, it was possible to obtain the complete structures using minimal quantities of polysaccharides A and B (8 and 5 mg, respectively). Only small amounts of each subjected to chemical analysis were not recoverable. Polysaccharide A is composed of the following repeating unit: [----3)alpha-D-AATp(1----4)[beta-D-Galf(1----3)]alpha-D- GalpNAc(1----3)beta-D-Galp(1----], where AAT is 2-acetamido-4-amino-2,4,6-trideoxygalactose. A pyruvate substituent having the R configuration spans O-4 and O-6 of the beta-D-galactopyranosyl residue. Polysaccharide B is composed of the following repeating unit: [----4)alpha-L-QuipNAc(1----3)beta-D-QuipNAc(1----4)[alpha-L - Fucp(1----2)beta-D-GalpA(1----3)beta-D-GlcpNAc(1----3)]alpha -D-Galp(1----]. A 2-aminoethylphosphonate substituent is situated on O-4 of the N-acetyl-beta-D-glucopyranosyl residue.
authors.affiliation: Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
authors.forename: H
authors.initials: H
authors.lastname: Baumann
authors.forename: A O
authors.initials: AO
authors.lastname: Tzianabos
authors.forename: J R
authors.initials: JR
authors.lastname: Brisson
authors.forename: D L
authors.initials: DL
authors.lastname: Kasper
authors.forename: H J
authors.initials: HJ
authors.lastname: Jennings
mesh_terms: D001441:Bacteroides fragilis / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005690:Galactose / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D011135:Polysaccharides, Bacterial; D005690:Galactose