The determination of glycopeptides by liquid chromatography/mass spectrometry with collision-induced dissociation

AbstractGlycopeptides derived from ribonuclease B and ovomucoid have been subjected to collision-induced dissociation (CID) in the second quadrupole of a triple quadrupole mass spectrometer. Doubly charged parent ions gave predictable fragmentation that yielded partial sequence information of the attached oligosaccharide as Hex and HexNAc units. Common oxonium ions are observed in the product ion mass spectra of the glycopeptides that correspond to HexNAc+ (m/z 204) and HexHexNAc+ (m/z 366). A strategy for locating the glycopeptides in the proteolytic digest mixtures of glycoproteins by ions spray liquid chromatography mass spectrometry (LC/MS) is described by utilizing CID in the declustering region of the atmospheric pressure ionization mass spectrometer to produce these characteristic oxonium ions. This LC/CID/MS approach is used to identify glycopeptides in proteolytic digest mixtures of ovomucoid, asialofetuin, and fetuin. LC/CID/MS in the selected ion monitoring mode may be used to identify putative glycopeptides from the proteolytic digest of fetuin

Ion spray-tandem mass spectrometry of supramolecular coordination complexes

Double-helical [M2L2]n+, triple-helical [M2L3]n+, and toroidal [M3L3]n+ (M = Cu, Co, Fe, Ni, La, Eu, Gd, Tb, or Lu) supramolecular complexes have been fully characterized by ion spray mass spectrometry (IS-MS). The IS-MS spectra from pure acetonitrile solutions reflect the nature of the cations present in solution with conservation of the charge state and allow an efficient qualitative speciation of the compounds. The mass spectrometry results can be correlated with other powerful techniques (nuclear magnetic resonance and electronic spectroscopy) for the characterization of supramolecular complexes in solution. Structural information is obtained by collision-induced dissociation, which strongly depends on the metal ions used in the supramolecular complexes and on the various connectivities and topologies of the ligands. When the ligand contains 3,5-dimethoxybenzyl groups bound to the benzimidazole rings, the partial fragmentation of the complexes is associated with a decrease of the total charge of the complexes and the appearance of the characteristic fragment at m/z 151 that corresponds to the 3,5-dimethoxybenzyl cation. A detailed analysis of the fragmentation pathways of these supramolecular complexes suggests that the metal-nitrogen coordination bonds are very strong in the gas phase

Application of Electrospray Mass Spectrometry for Characterizing Supramolecular Coordination Complexes

The Electrospray Mass Spectrometry (ES-MS) of eight different supramolecular complexes shows that the molecular peaks of the desolvated multiply charged cations can be recorded more easily than by Fast-Atom-Bom-bardment Mass Spectrometry (FAB-MS) measurements of similar compound. The preliminary application of the ES-MS technique to self-assembled helical complexes obtained from ligands L3 to L8 with various metal ions (Cu, Co, Eu, Tb) indicates that ES mass spectra qualitatively reflect the species present MeCN solution