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Applications of a matrix‐assisted laser desorption/ionization orthogonal time‐of‐flight mass spectrometer. l. Metastable decay and collision‐induced dissociation for sequencing peptides
Author(s) -
Ackloo Suzanne,
Loboda Alexandre
Publication year - 2004
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/rcm.1775
Subject(s) - chemistry , mass spectrometry , ionization , analytical chemistry (journal) , collision induced dissociation , ion , fragmentation (computing) , dissociation (chemistry) , time of flight mass spectrometry , mass spectrum , ion source , chromatography , surface enhanced laser desorption/ionization , protein mass spectrometry , tandem mass spectrometry , organic chemistry , computer science , operating system
The use of a high‐performance orthogonal time‐of‐flight (o‐TOF) mass spectrometer for sequence analysis is described. The mass spectrometer is equipped with a matrix‐assisted laser desorption/ionization (MALDI) source that operates at elevated pressure, 0.01–1 Torr. Ion fragmentation is controlled by varying the pressure of the buffer gas, the laser energy, the voltage difference between the MALDI target and the adjacent sampling cone, and between the cone and the quadrupole ion guide. The peptides were analyzed under optimal ionization conditions to obtain their molecular mass, and under conditions that promote ion dissociation via metastable decomposition or collision‐induced dissociation (CID). The fragmentation spectra were used to obtain sequence information. Ion dissociation was promoted via three configurations of the ionization parameters. All methods yielded sequencing‐grade b‐ and y‐type ions. Two binary mixtures of peptides were used to demonstrate that: (1) external calibration provides a standard deviation ( σ ) of 4 ppm with a mode of 9 ppm; and (2) that peptides with molecular masses that differ by a factor of two may be independently fragmented by appropriately choosing the CID energy and the low‐mass cut‐off. Analyses of tryptic digests employed liquid chromatography (LC), deposition of the eluant on a target, and finally MALDI‐TOF mass spectrometry. The mass fingerprint and the (partial) sequence of the tryptic peptides were matched to their precursor protein via database searches. Copyright © 2004 John Wiley & Sons, Ltd.