title: Tandem mass spectrometry and infrared spectroscopy as a tool to identify peptide oxidized residues.
abstract: The final products obtained by the oxidation of small model peptides containing the thioether function, either methionine or S-methyl cysteine, have been characterized by tandem mass spectrometry and IR Multiple Photon Dissociation (IRMPD) spectroscopy. The modified positions have been clearly identified by the CID-MS(2) fragmentation mass spectra with or without loss of sulfenic acid, as well as by the vibrational signature of the sulfoxide bond at around 1000 cm(-1). The oxidation of the thioether function did not lead to the same products in these model peptides. The sulfoxide and sulfone (to a lesser extent) have been clearly identified as final products of the oxidation of S-methyl-glutathione (GS-Me). Decarboxylation or hydrogen loss are the major oxidation pathways in GS-Me, while they have not been observed in tryptophan-methionine and methionine-tryptophan (Trp-Met and Met-Trp). Interestingly, tryptophan is oxidized in the dipeptide Met-Trp, while that is not the case in the reverse sequence (Trp-Met).
authors: Laboratoire de Chimie Physique, Université Paris Sud, 91405 Orsay Cedex, France. debora.scuderi@u-psud.fr.
authors: D
authors: D
authors: Scuderi
authors: M T
authors: MT
authors: Ignasiak
authors: X
authors: X
authors: Serfaty
authors: P
authors: P
authors: de Oliveira
authors: C
authors: C
authors: Houée Levin
mesh_terms: D004151:Dipeptides / Q000737:chemistry*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared / Q000379:methods; D013450:Sulfones / Q000032:analysis; D013454:Sulfoxides / Q000032:analysis; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D004151:Dipeptides; D013450:Sulfones; D013454:Sulfoxides; C075587:methionyltryptophan; D005978:Glutathione; C017514:S-methyl glutathione