Structural analysis of oligosaccharides by atmospheric pressure matrix‐assisted laser desorption/ionisation quadrupole ion trap mass spectrometry

Abstract

An ion source incorporating a fibre optic interface has been constructed for atmospheric pressure matrix-assisted laser desorption/ionisation quadrupole ion trap mass spectrometry. The configuration has been applied to the study of linear and complex oligosaccharides. Multi-stage tandem mass spectrometry (MSn, n = 2-4) experiments carried out in the ion trap enable extended fragmentation pathways to be investigated that yield structural information. Collisional activation of sodiated oligosaccharides, as demonstrated on the model compound maltoheptaose, produces primarily B and Y fragments resulting from cleavage of glycosidic bonds; fragments from cross-ring cleavages are also observed following further stages of tandem mass spectrometry, providing additional linkage information. The analyses of mixtures of complex oligosaccharides are demonstrated for N-linked glycans from chicken egg glycoproteins and a ribonuclease glycan mixture. Mass spectrometric and tandem mass spectrometric data for sugars with molecular weights up to 4000 Da is shown for mixtures of linear dextrans and N-linked glycans. The use of MSn (n = 3, 4) on these complex molecules enabled structural information to be elucidated that confirms data observed in the MS/MS spectra.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update covering the period 2001–2002

“…Work from Costello's group suggests that 6-azo-2-thiothymine (ATT, 1/45) is a better matrix under these conditions. Spectra from the article by Creaser, Reynolds, and Harvey (2002) showed more in-source fragmentation, particularly losses of water, than those recorded in vacuo but fragmentation within the ion trap was similar to that seen following ionization by other methods. Pressure at an estimated 1-10 mbar in a pulsed MALDI ion source attached to a Fourier-transform (FT) mass spectrometer has been reported to prevent both fragmentation of peptides and loss of sialic acid (Neu5Ac, 1/11) from the ganglioside GT1b (a-Neu5Ac-(2 !…”

“…Collisional cooling of the ion beam is necessary to modulate the pulsed nature of the ion source. Creaser, Reynolds, and Harvey (2002) have interfaced an atmospheric pressure ion source to a Finnigan ion trap mass spectrometer and found that, unlike vacuum MALDI, esculetin (1/73) ionized carbohydrates more efficiently than DHB. Work from Costello's group suggests that 6-azo-2-thiothymine (ATT, 1/45) is a better matrix under these conditions.…”

AP/MALDI‐MS complete characterization of the proteolytic fragments produced by the interaction of insulin degrading enzyme with bovine insulin

“…Atmospheric pressure/matrix assisted laser desorption ionization (AP/MALDI) MS has already proved to be a very valuable tool in a number of important applications, including the identification of proteins,26 the structural analysis of oligosaccharides,27 the characterization of enzymes immobilized on solid support,28 and the study of phosphopeptides,29 due to its ability to detect intact molecular masses up to several 1000 Da 30…”

Glycomics and Mass Spectrometry

“…This instrument was applied to the analysis of the neutral oligosaccharide, difucosyllacto-N-tetraose [274]. UV AP-MALDI coupled to an ion trap mass spectrometer was used by Creaser et al [275] to acquire MS n spectra of sodium adducts of neutral oligosaccharides and by Moyer et al for the negative mode analyses of sialylated oligosaccharides [276]. More recently, the analysis of sialylated oligosaccharides using infrared atmospheric pressure matrix assisted laser desorption/ionisation on an ion trap mass spectrometer (IR AP-MALDI-ITMS) has been reported [277,278].…”