Distinctive mass losses of tryptic peptides generated by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight

2006 ◽  
Vol 20 (5) ◽  
pp. 933-936 ◽  
Author(s):  
Frank Schmidt ◽  
Alexander Krah ◽  
Monika Schmid ◽  
Peter R. Jungblut ◽  
Bernd Thiede
Keyword(s):  
Time Of Flight ◽  
Laser Desorption ◽  
Flight Time ◽  
Laser Desorption Ionization ◽  
Tryptic Peptides ◽  
Ionization Time ◽  
Desorption Ionization ◽  
Mass Losses ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

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

2007 ◽  
Vol 13 (5) ◽  
pp. 347-353 ◽  
Author(s):  
Josef Chmelík ◽  
Pavel Řehulka ◽  
Vladimír Kováčik ◽  
Vladimír Pätoprstý ◽  
Pavol Kováč
Keyword(s):  
Mass Spectrometry ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Flight Time ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

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 MALDI/MS analysis conditions 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 number 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.

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