Negative-mode MALDI-TOF/TOF-MS of oligosaccharides labeled with 2-aminobenzamide

Anal Chem. 2005 Nov 1;77(21):6954-9. doi: 10.1021/ac051117e.

Abstract

MALDI-TOF-MS of 2-aminobenzamide-labeled N-glycans was shown to allow the analysis of sodium adducts and proton adducts in the positive-ion mode as well as deprotonated species in the negative-ion mode from a single preparation spot, using N-glycans of adult worms of the human parasite Schistosoma mansoni as model substances. Fragment ion analysis of these species was performed by MALDI-TOF/TOF-MS. With laser-induced dissociation, sodium adducts and proton adducts mainly showed cleavage of glycosidic linkages. High-energy collision-induced dissociation of sodium adducts resulted in extensive cross-ring cleavages and provided information on linkage positions. Of particular value were the negative-mode MALDI-TOF/TOF-MS analyses of the deprotonated N-glycans, which featured (1) various ring fragmentations giving linkage information, (2) extensive (1,3)A cross-ring cleavage of mannoses carrying an antenna readily revealing the composition of the antenna, (3) D as well as [D-18]- ions providing specifically the composition of the 6-antenna, and (4) pronounced stability of fucose linkages resulting in detailed information on fucosylation positions. The outlined approach thus allows the acquisition of both heCID MS/MS spectra of sodium adducts and LID MS/MS spectra of deprotonated species from a 2-aminobenzamide-labeled N-glycan prepared in 6-aza-2-thiothymine, resulting in a wealth of structural information.

MeSH terms

  • Animals
  • Carbohydrate Conformation
  • Oligosaccharides / chemistry*
  • Oligosaccharides / metabolism
  • Protons
  • Schistosoma mansoni / metabolism
  • Sodium / chemistry
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Thymine / analogs & derivatives
  • Thymine / chemistry
  • Triazines
  • ortho-Aminobenzoates / chemistry*

Substances

  • Oligosaccharides
  • Protons
  • Triazines
  • ortho-Aminobenzoates
  • 2-thio-6-azathymine
  • Sodium
  • anthranilamide
  • Thymine