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

Abstract

Oligosaccharides (tri- to hexamers) that represent terminal epitopes of O-antigens of Vibrio cholerae O:1, serotypes Ogawa and Inaba, have been studied by negative matrix-assisted laser desorption/ionization time of flight/time-of-flight mass spectrometry (MALDI ToF/ToF MS). The [M - H(+)](-) ions are formed after expulsion of a proton from molecules studied under condition of MALDI MS analysis in the negative mode. Several ammonium salts (chloride, nitrate, hydrogencarbonate and hydrogensulfate) were used as additives to increase the formation of negative ions from saccharides. The most efficient was the addition of ammonium hydrogencarbonate, which increased the amount of [M - H(+)](-) ions more than six times. Between three fragmentation pathways, the new conjugated transfer of electrons within the second downstream unit of oligosaccharides was discovered. Production of these ions, which has not been observed in any other kinds of measurement, distinguishes substances belonging to Ogawa and Inaba serotypes. The negative MALDI ToF/ToF mass spectra are simpler and, at the same time, more informative, as compared with positive and negative electrospray ionization ion trap as well as with positive MALDI ToF/ToF analysis.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

“…Alternatively, some investigators have adducted carbohydrates with anions such as chloride and sulfate and observed strong signals. Chmelík et al (2007) have investigated the addition of ammonium chloride, nitrate, hydrogen-carbonate and hydrogen-sulfate to DHB or THAP and report that hydrogen-carbonate appears to produce the most intense [M þ H] À ions without adduct formation. The most abundant adducts were formed with nitrate ([M þ NO 3 ] À ).…”

Mass Spectrometry in Pharmacokinetic Studies of a Synthetic Compound for Spinal Cord Injury Treatment

“…Saccharides and oligonucleotides are usually analyzed under negative ionization conditions [ 8 , 9 ]. We obtained the IG20 glycoside as a unique final product of a chemical synthesis process [ 6 ].…”

Fragmentation analysis of O-specific polysaccharide from bacteria Vibrio cholerae O139 by MALDI-TOF and LC/ESI-MS/MS

“…13 For fragmentation analysis of OSP of V. cholerae O1, negative matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF)/TOF and positive and negative ESI-MS/ MS analyzes were used. 14,15,16 MALDI-TOF/TOF and ESI-MS/MS analyzes were also used for fragmentation analysis of bacterial LPSs, lipooligosaccharides and O-antigens of other bacteria, such as Neisseria meningitidis, Escherichia coli or Vibrio fischeri. [17][18][19][20] In this work, structural and fragmentation analyzes of the OSP and core part of LPS isolated from V. cholerae O139 were performed by i.)…”