title: Structural characterization of underivatized arabino-xylo-oligosaccharides by negative-ion electrospray mass spectrometry.
abstract: Various arabino-xylo-oligosaccharides with known substitution patterns were assessed by negative ESI-Q-TOFMS and ESI-ITMS. The CID spectra of linear xylo-oligosaccharides and of nine isomeric mono- and disubstituted arabino-xylo-oligosaccharides established that structures differing in their substitution pattern can be differentiated by this approach. The negative-ion fragmentation spectra of the deprotonated quasi-molecular ions are mainly characterized by glycosidic cleavage ions from the C-series, which provide sequence informations, and by cross-ring cleavage (0,2)A(i) ions, which provide partial linkage information. When the collision energy increased, the cross-ring cleavage (0,2)A(i) ions underwent consecutive loss of water to produce (0,2)A(i)-18 fragment ions and glycosidic cleavage ions of the B-series are also produced besides the C(i) ions. Contrary to linear xylo-oligosaccharides, C(i) ions, which originate from C-3 monosubstituted xylosyl residues never produce the related cross-ring cleavage (0,2)A(i) ions. Disubstitution at O-2 and O-3 of xylosyl residues appears to enhance the production of the (0,2)A(i) ions compared to monosubstitution. For the differentiation of the mono- and disubstitution patterns of the penultimate xylosyl residue, the relative abundance of the glycosidic cleavage ions at m/z 263 and 299 found on Q-TOF CID spectra plays a relevant role and appears to be more informative than MS(n) spectra obtained on a ion trap instrument.
authors.affiliation: INRA-Biopolymères, Interactions, Assemblages-Rue de la Géraudière BP 71627, Nantes, France. bernard.quemener@nantes.inra.fr
authors.forename: Bernard
authors.initials: B
authors.lastname: Quéméner
authors.forename: José Juan
authors.initials: JJ
authors.lastname: Ordaz-Ortiz
authors.forename: Luc
authors.initials: L
authors.lastname: Saulnier
mesh_terms: D001089:Arabinose / Q000032:analysis*; D002240:Carbohydrate Sequence; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D006868:Hydrolysis; D015394:Molecular Structure; D008970:Molecular Weight; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014908:Triticum / Q000737:chemistry; D014990:Xylans / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D014994:Xylose / Q000032:analysis*
chemical_list: D009844:Oligosaccharides; D014990:Xylans; D014994:Xylose; D001089:Arabinose; D043364:Endo-1,4-beta Xylanases