Positive electrospray ion trap multistage mass spectrometric fragmentation of synthetic analogs of saccharide part of lipopolysaccharides of Vibrio cholerae O:1

Abstract

Oligosaccharides (mono- to hexamers) that mimic the terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba, have been studied by electrospray ion trap (ESI IT) mass spectrometry. Sodium or potassium-cationized adducts are characteristic ions under the conditions of ESI-MS analysis. The tentative pathways of fragmentation have been proven by multistage ion trap MS (MS(n), n = 1-3). The predominant pathway of fragmentation of the oligomers is the neutral loss of monosaccharide residue shortening the length of the oligosaccharide. In this way, conversion of the Ogawa to Inaba fragments takes place under the conditions of measurement. ESI MS/MS provided sufficient information about molecular mass, the number of saccharide residues, and the structure of saccharides, about the C (4)-amide of 3-deoxy-L-glycero-tetronic acid (DGT) of the compounds investigated, and allows to distinguish between Ogawa and Inaba serotypes.

Negative Matrix-Assisted Laser Desorption/Ionization Time-of-Flight/Time-of-Flight Tandem Mass Spectrometry Fragmentation of Synthetic Analogs of the O-Specific Polysaccharide of Vibrio Cholerae O:1 in the Presence of Anionic Dopants

“…[9][10][11] A comparison of the MS spectra of the oligomers of Ogawa and Inaba types confirms that the leaving residue in the first step of the chain-shortening pathway is the terminal upstream mannose unit with the C(2) hydroxyl or methoxyl group. Formally, the chain shortening pathways resembled the Y (nomenclature introduced by Domon and Costello 27 ) fast atom bombardment fragmentation pathway of oligosaccharides.…”

“…8 More recently, we studied synthetic mono-to hexasaccharides that mimic the fragments of O-PS by electrospray multistage ion trap mass spectrometry in the positive mode. 9 The main feature of this fragmentation is the step-by-step shortening of the length of oligosaccharides. Characteristic feature of the electrospray ionization ion trap (ESI/IT) negative fragmentation is stepwise elimination of the C-4 N-acyl groups in the form of α-hydroxy-γ-butyrolactone molecules.…”

Negative Electrospray, Ion Trap Multistage Mass Spectrometry of Synthetic Fragments of the O-PS of Vibrio Cholerae O:1

“…24 Fragmentation of tetra-and higher oligosaccharides involves almost exclusively stepwise elimination of α-hydroxy-γ-butyrolactone, as shown in Figure 7 for the example of pentamer 5 Og. In the MS 3 and higher multistage spectra, elimination of other molecules of HBL (less 102 mu) was observed. Example routes ( Figure 7) show formation of cc 5 , ccc 5 , cccc 5 and ccccc 5 species in the second to the fifth steps of the fragmentation.…”

“…Negative ion ESI MS [1][2][3] were measured using an Esquire 3000 ion-trap mass spectrometer (Bruker Daltonik, Bremen, Germany) equipped with an electrospray ionization source. 1 mg of the sample was dissolved in 1 mL of acetonitrile/water 1 : 1.…”

“…1,2 In continuation of the study, fragmentation of �M + Na� + positive ions, obtained by electrospray multistage ion trap mass spectrometry (ESI IT MS n , n �� 1-3) was elucidated. 3 Recent work suggests that fragmentation of negative ions of carbohydrates gives complementary information with, in many cases, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] additional fragmentation that can reveal finer details of the structure. Here, we studied synthetic mono-to hexasaccharides ( Figure 1) that mimic the synthetic fragments of the O-antigen of Ogawa and Inaba O-PS.…”