Negative-mode MALDI-TOF/TOF-MS of oligosaccharides labeled with 2-aminobenzamide.
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.
Wuhrer
Manfred
M
Biomolecular Mass Spectrometry Unit, Department of Parasitology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. m.wuhrer@lumc.nl
Deelder
André M
AM
D000818:Animals; D002236:Carbohydrate Conformation; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D011522:Protons; D012550:Schistosoma mansoni / Q000378:metabolism; D012964:Sodium / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013941:Thymine / Q000031:analogs & derivatives / Q000737:chemistry; D014227:Triazines; D062367:ortho-Aminobenzoates / Q000737:chemistry*
D009844:Oligosaccharides; D011522:Protons; D014227:Triazines; D062367:ortho-Aminobenzoates; C005823:2-thio-6-azathymine; D012964:Sodium; C000219:anthranilamide; D013941:Thymine