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Post‐translational modification detection using metastable ions in reflector matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry
Author(s) -
Wirth Urs,
Müller Dieter,
Schindler Patrick,
Lange Joerg,
van Oostrum Jan
Publication year - 2002
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/1615-9861(200210)2:10<1445::aid-prot1445>3.0.co;2-7
Subject(s) - mass spectrometry , chemistry , orbitrap , metastability , ion , ionization , mass spectrum , matrix assisted laser desorption/ionization , protein mass spectrometry , top down proteomics , proteomics , matrix (chemical analysis) , fourier transform ion cyclotron resonance , analytical chemistry (journal) , desorption , electrospray ionization , chromatography , biochemistry , organic chemistry , adsorption , gene
In addition to protein identification, characterization of post‐translational modifications (PTMs) is an essential task in proteomics. PTMs represent the major reason for the variety of protein isoforms and they can influence protein structure and function. Upon matrix‐assisted laser desorption/ionization (MALDI) most post‐translationally modified peptides form a fraction of labile molecular ions, which lose PTM‐specific residues only after acceleration. Compared to fully accelerated ions these fragment ions are defocused and show in reflector mass spectra reduced resolution. A short time Fourier transform using a Hanning window function now uses this difference in resolution to detect the metastable fragments. Its application over the whole mass range yields frequency distributions and amplitudes as a function of mass, where an increased low frequency proportion is highly indicative for metastable fragments. Applications on the detection of metastable losses originating from carboxamidomethylated cysteines, oxidized methionines, phosphorylated and glycosylated amino acid residues are presented. The metastable loss of mercaptoacetamide detected with this procedure represents a new feature and its integration in search algorithms will improve the specificity of MALDI peptide mass fingerprinting.