title: Electron capture dissociation of oligosaccharides ionized with alkali, alkaline Earth, and transition metals.
abstract: We extend the application of electron capture dissociation (ECD) (which requires at least two charges) to oligosaccharides without basic functionalities by utilizing alkali, alkaline earth, and transition metals (Na+, K+, Ca2+, Ba2+, Mg2+, Mn2+, Co2+, and Zn2+) as charge carriers in electrospray ionization. Both linear and branched oligosaccharides were examined, including maltoheptoase, p-lacto-N-hexaose, and an N-linked glycan from human alpha1-acid glycoprotein. For comparison, infrared multiphoton dissociation (IRMPD) was also applied to all oligosaccharide species. We show that, for certain metal-adducted oligosaccharides, particularly maltoheptaose, cross-ring cleavage, which can provide saccharide linkage information, is the dominant fragmentation pathway in ECD. By contrast, glycosidic cleavages dominate in IRMPD although cross-ring fragmentation was also observed to varying degrees depending on metal ion type. The branched N-linked glycan did not fragment as easily following ECD compared to the linear oligosaccharides, presumably due to intramolecular noncovalent interactions. However, this limitation was partially overcome with a combined ECD/IRMPD approach (activated ion ECD). For all metal-adducted oligosaccharides, complementary structural information was obtained with ECD as compared to IRMPD. Our results demonstrate that ECD of metal-adducted oligosaccharides is a valuable tool for structural characterization of oligosaccharides.
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA.
authors.forename: Julie T
authors.initials: JT
authors.lastname: Adamson
authors.forename: Kristina
authors.initials: K
authors.lastname: Håkansson
mesh_terms: D004583:Electrons; D008672:Metals, Alkali / Q000737:chemistry*; D008673:Metals, Alkaline Earth / Q000737:chemistry*; D009844:Oligosaccharides / Q000032:analysis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D008672:Metals, Alkali; D008673:Metals, Alkaline Earth; D009844:Oligosaccharides; D028561:Transition Elements