title: Structures of the O-linked oligosaccharides of a complex glycoconjugate from Pseudallescheria boydii.
abstract: Nonreducing O-linked oligosaccharides were obtained from the peptidorhamnomannan of mycelia of Pseudallescheria boydii by alkaline beta-elimination under reducing conditions. They were separated by gel filtration chromatography to give three oligosaccharide fractions. The major oligosaccharide from fraction 1 was characterized by a combination of techniques including electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI MS/MS), matrix-assisted laser desorption ionization mass spectrometry (MALDI MS), nuclear magnetic resonance (NMR), and methylation gas-liquid chromatography-mass spectrometry (GC-MS) analysis. It was branched, with a principal chain of alpha-Rhap-(1 --> 3)-alpha-Rhap-(1 --> 3)-alpha-Manp-(1 --> 2)-Man-ol substituted at O-6 of mannitol with an alpha-Glcp-(1 --> 4)-beta-Galp group. Species containing one and two additional alpha-Glcp-(1 --> 4) substituents in the rhamnose branch were also present. The major component of fraction 2 was a substructure of oligosaccharide-1, lacking a hexose from the Glc-Gal branch. Fraction 3 contained a mixture of smaller, unbranched, oligosaccharides. In hapten inhibition tests, fractions 1 and 2 blocked the reaction between peptidorhamnomannan (PRM) and rabbit anti-P. boydii mycelium hyperimmune serum by approximately 75%, whereas fraction 3 inhibited by approximately 55%.
authors.affiliation: Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, CCS, Bloco I, Ilha do Fundão, Rio de Janeiro, RJ 21941-970, Brazil.
authors.forename: Marcia R
authors.initials: MR
authors.lastname: Pinto
authors.forename: Philip A J
authors.initials: PA
authors.lastname: Gorin
authors.forename: Robin
authors.initials: R
authors.lastname: Wait
authors.forename: Barbara
authors.initials: B
authors.lastname: Mulloy
authors.forename: Eliana
authors.initials: E
authors.lastname: Barreto-Bergter
mesh_terms: D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006001:Glycoconjugates / Q000737:chemistry*; D007106:Immune Sera; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D025942:Oligosaccharides, Branched-Chain / Q000737:chemistry* / Q000276:immunology; D011541:Pseudallescheria / Q000737:chemistry* / Q000276:immunology; D011817:Rabbits; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D006001:Glycoconjugates; D007106:Immune Sera; D025942:Oligosaccharides, Branched-Chain