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Differentiation of ‘isobaric’ peptides and human milk oligosaccharides by exact mass measurements using electrospray ionization orthogonal time‐of‐flight analysis
Author(s) -
Bahr U.,
Karas M.
Publication year - 1999
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19990615)13:11<1052::aid-rcm604>3.0.co;2-y
Subject(s) - chemistry , isobaric process , electrospray ionization , mass spectrometry , chromatography , isobaric labeling , mass , protein mass spectrometry , analytical chemistry (journal) , ion , collision induced dissociation , electrospray , amino acid , ionization , time of flight mass spectrometry , molecular mass , mass spectrum , tandem mass spectrometry , organic chemistry , biochemistry , thermodynamics , physics , enzyme
Exact mass determination is performed by electrospray ionization orthogonal time‐of‐flight mass analysis. For peptides in the mass range of 1200–1500 Da a mass error of <5 ppm is achieved with internal calibration within a single mass measurement provided peak intensities are high. Peptides containing isobaric amino acids like glutamine and lysine can thus be easily differentiated by their mass. In cases where more than one of these isobaric amino acids are present, the position of the amino acid can be revealed by exactly determining the mass differences between adjacent Y i ″ fragment ions in the collision‐induced dissociation spectrum. Mass determination accuracy can be enhanced to 0.5–2 ppm by averaging over 8–10 mass measurements. Thereby compositional analysis of human milk oligosaccharides in a mixture can be performed in the mass range up to 3000 Da, even for low‐intensity molecule‐ion signals and for isobaric compounds with a mass difference of only 0.025 Da. Copyright © 1999 John Wiley & Sons, Ltd.