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Identification of oxidized methionine residues in peptides containing two methionine residues by derivatization and matrix‐assisted laser desorption/ionization mass spectrometry
Author(s) -
Hollemeyer Klaus,
Heinzle Elmar,
Tholey Andreas
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(200211)2:11<1524::aid-prot1524>3.0.co;2-7
Subject(s) - methionine sulfoxide , chemistry , methionine , cyanogen bromide , mass spectrometry , matrix assisted laser desorption/ionization , peptide , derivatization , sulfoxide , amino acid , chromatography , desorption , organic chemistry , peptide sequence , biochemistry , adsorption , gene
Oxidation of methionine residues in peptides and proteins occurs in vivo or may be an artifact resulting from purification steps. We present a three step method for the localization of methionine sulfoxides in peptides with two methionine residues. In the first step, the N ‐terminus as well as other reactive side chain functions are blocked by acetylation. The resulting protected peptides are cleaved by cyanogen bromide. The cleavage does not occur at methionine sulfoxide but only at reduced methionine residues forming new amino termini. The newly formed amino group is then derivatized with a bromine containing compound in the last step of the procedure. The resulting peptide can easily be identified by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry using both the characteristic isotope pattern of the halogen and the metastable loss of methanesulfenic acid from oxidized residues. This procedure allows the unequivocal localization of oxidized methionines even in complex peptide mixtures.