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Oxidation of carboxyamidomethyl cysteine may add complexity to protein identification
Author(s) -
Yagüe Jesús,
Núñez Antonio,
Boix Manuel,
Esteller Manel,
Alfonso Patricia,
Casal J. Ignacio
Publication year - 2005
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/pmic.200401189
Subject(s) - dehydroalanine , chemistry , peptide , sulfoxide , cysteine , tandem mass spectrometry , isobaric labeling , native chemical ligation , combinatorial chemistry , amino acid , mass spectrometry , tandem mass tag , database search engine , sulfone , peptide sequence , peptide mass fingerprinting , biochemistry , chromatography , proteomics , organic chemistry , protein mass spectrometry , computer science , quantitative proteomics , information retrieval , gene , enzyme , search engine
Protein identification by interrogation of databases requires a comprehensive compilation of modified amino acids forms. Here, we describe the chemical oxidation of carboxyamidomethyl cysteine to the sulfoxide and sulfone forms, species that may add more complexity to peptide analyses. They can be easily distinguished by tandem mass spectrometry (MS/MS) due to their characteristic pattern of side chain neutral eliminations either from the parent ion or ion series that generate dehydroalanine as detected by MS 3 . This finding was supported by the MS n spectra recorded for a peptide isolated from a mixture of tryptic peptides and for a derivatized/oxidized synthetic peptide with a different sequence. These modifications and their diagnostic neutral losses should be included in the list of chemical modifications and in algorithms designed for the automatic sequencing of peptides and database searching.