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Advantages of derivatization by osmium tetroxide and 2,2′‐bipyridine for matrix‐assisted laser desorption/ionization post‐source decay fragment ion analysis of peptides
Author(s) -
Šedo O.,
Novotná K.,
Havel J.
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.1339
Subject(s) - chemistry , cysteic acid , matrix assisted laser desorption/ionization , peptide , derivatization , osmium tetroxide , reagent , fragmentation (computing) , cysteine , mass spectrometry , chromatography , desorption , organic chemistry , biochemistry , cystine , electron microscope , physics , computer science , optics , enzyme , operating system , adsorption
Matrix‐assisted laser desorption/ionization—post‐source decay (MALDI‐PSD) fragment ion analysis is frequently used for peptide sequence determination. PSD fragmentation is often changed or improved in terms of, e.g., sequence coverage, after derivatization. In this work, the influence of modification by an osmium tetroxide‐bipyridine reagent (Os,bipy) on the MALDI‐PSD behaviour of peptides is studied. The reagent modifies peptides specifically at tryptophan residues and oxidizes methionine to methionine sulfone and cysteine to cysteic acid. As a result the masses of some of the fragments are specifically shifted in case of peptides containing a methionine by +32 Da and, in cases of peptides containing a cysteine residue, by +48 Da. In addition, due to the change in protonation properties of a peptide after oxidation, fragments containing cysteic acid are in most cases totally suppressed. This effect significantly facilitates peptide sequence determination. Improvement of MALDI‐TOFMS and PSD analysis after the reaction with Os,bipy is demonstrated for examples involving derivatives of humanin, a novel neuroprotective peptide. Copyright © 2004 John Wiley & Sons, Ltd.