Dominique Despeyroux

Collision-induced dissociation of alkali metal cationized and permethylated oligosaccharides: Influence of the collision energy and of the collision gas for the assignment of linkage position

Tandem mass spectrometry has been used to study the collision-induced decomposition of [M+Na]+ ions of permethylated oligosaccharides. It is shown that many linkage positions in one compound may be determined by the presence or absence, in a single spectrum, of specific fragment ions that arise from the cleavage of two ring bonds and that the yield of such ions depends strongly on the collision energy and nature of the collision gas. In contrast to the behavior of monolithiated native oligosaccharides, the collision-induced decomposition of the sodiated and permethylated oligosaccharide samples at low energy leads to preferential cleavage of glycosidic linkages. At high collision energies, the fragment ions formed by cleavage of more than one bond are greatly enhanced, especially when helium is replaced by argon as the collision gas. Furthermore, argon is the more efficient collision gas in inducing fragmentation of the precursor ions. As an example of the application of this method, the discrimination between the 1 → 3 and 1 → 6-linked mannose residues in the common core of N-glycans is described.

Comparison of helium and argon as collision gases in the high energy collision-induced decomposition of MH+ ions of peptides

Collision-induced decompositions (CID) of protonated peptides were studied using a four-sector mass spectrometer. The collision gases employed were helium and argon. The CID spectra of several peptides covering the molecular mass region of 905–2465 u were recorded. These investigations established several previously unrecognized differences between the CID spectra obtained with helium and argon as collision gases. These can be summarized as follows: (1) Structurally significant and specific side chain fragmentations (dnf, wnf and vn, ion types) are greatly reduced or completely missing in the CID spectra obtained with helium as a collision gas compared to those obtained with argon. (2) As the peptide molecular mass increases, argon, which is heavier than helium, is increasingly more efficient than helium for generating fragment ions.

Charge Remote Losses of Small Neutrals from Protonated and Group 1 Metal–Peptide Complexes of Peptides

The fragmentations of alkali metal–peptide complexes of the form [M + Cat]+ have been studied by means of high and low energy tandem mass spectrometry. Small neutral losses from the precursor ion can be attributed to charge remote fragmentations along the pendant chains of certain amino acids such as arginine, lysine and methionine. The losses vary according to the structure of the amino acid side chain and in some instances provide a rapid means of verifying the absence or presence of one of these residues.

The effect of collision energy and nature of the surface on the surface-induced dissociation mass spectra of fluorobenzene using a four-sector mass spectrometer

Abstract The effects on the surface-induced mass spectrum of fluorobenzene, recorded using a four-sector mass spectrometer, of changing the collision energy and the nature of the surface are reported. At higher collision energies, although the overall ion current is reduced, the relative abundance of product ions is increased, particularly those of low m/z . The use of a rough surface, such as a film of PTFE, increases the abundance of low mass fragment ions for a given translational energy, especially at higher collision energies.

Comparison of collision-induced dissociation and surface-induced dissociation mass spectra of peptides obtained using a four-sector mass spectrometer☆

Abstract The high energy argon CID and 100 eV surface-induced dissociation mass spectra of MH + ions of three peptides of RMM 1300—1850 Da are reported and compared. The fragmentation patterns of these ions are discussed in terms of the nature of the ions produced in each case. The SID mass spectra resemble more closely those produced by low rather than high energy CID obtained using hybrid tandem was spectrometers. This observation suggests that, with the device used for these SID experiments, only a small amount of the kinetic energy of the precursor ions is converted to internal energy.

THE OBSERVATION OF BROAD METASTABLE ION PEAKS IN THE SURFACE-INDUCED DISSOCIATION MASS SPECTRA OF PROTONATED AND CATIONATED PEPTIDES

Abstract The product ion mass spectra of protonated and cationated peptides of relative molecular mass (RMM) 555–574 Da have been obtained by surface-induced dissociation of MH+ and [M + Cat]− ions in a four-sector tandem mass spectrometer equipped with a specially designed collision cell. A linked scan of the electric and magnetic sector field strengths of the second mass spectrometer was used to transmit the fragment ions arising from collisions with a stainless steel surface. The resulting mass spectra contained broad metastable ion peaks produced by the dissociation of MH+ and [M + Cat]+ ions before the second magnetic sector, in the fourth field-free region of the instrument.