title: Characterization of the glycosidic linkage of underivatized disaccharides by interaction with Pb(2+) ions.
abstract: Electrospray ionization in combination with tandem mass spectrometry and lead cationization is used to characterize the linkage position of underivatized disaccharides. Lead(II) ions react mainly with disaccharides by proton abstraction to generate [Pb(disaccharide)(m)-H](+) ions (m = 1-2). At low cone voltages, an intense series of doubly charged ions of general formula [Pb(disaccharide)(n)](2+) are also observed. Our study shows that MS/MS experiments have to be performed to differentiate Pb(2+)-coordinated disaccharides. Upon collision, [Pb(disaccharide)-H](+) species mainly dissociate according to glycosidic bond cleavage and cross-ring cleavages, leading to the elimination of C(n)H(2n)O(n) neutrals (n = 2-4). The various fragmentation processes allow the position of the glycosidic bond to be unambiguously located. Distinction between glc-glc and glc-fru disaccharides also appears straightforward. Furthermore, for homodimers of D-glucose our data demonstrate that the anomericity of the glycosidic bond can be characterized for the 1 --> n linkages (n = 2, 4, 6). Consequently, Pb(2+) cationization combined with tandem mass spectrometry appears particularly useful to identify underivatized disaccharides.
authors.affiliation: Université d'Evry Val d'Essonne--Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, CNRS, Bâtiment Maupertuis, Boulevard François Mitterrand, 91025 EVRY, France.
authors.forename: Ahlam El
authors.initials: AE
authors.lastname: Firdoussi
authors.forename: Marie
authors.initials: M
authors.lastname: Lafitte
authors.forename: Jeanine
authors.initials: J
authors.lastname: Tortajada
authors.forename: Omar
authors.initials: O
authors.lastname: Kone
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Salpin
mesh_terms: D002413:Cations, Divalent / Q000737:chemistry; D002475:Cellobiose / Q000737:chemistry; D004187:Disaccharides / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D002413:Cations, Divalent; D004187:Disaccharides; D006027:Glycosides; D009566:Nitrates; D009942:Organometallic Compounds; C014637:laminaribiose; D002475:Cellobiose; D007854:Lead; C017461:lead nitrate; C100052:gentiobiose