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Selective detection of thiosulfate‐containing peptides using tandem mass spectrometry
Author(s) -
Raftery Mark J.
Publication year - 2005
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.1840
Subject(s) - chemistry , mass spectrometry , peptide , chromatography , tandem mass spectrometry , fast atom bombardment , protein mass spectrometry , thiosulfate , high performance liquid chromatography , collision induced dissociation , sodium thiosulfate , sulfur , organic chemistry , biochemistry
Incubation of proteins or peptides containing disulfide bonds (SS) with sodium sulfite (Na 2 SO 3 ) cleaves SS bonds producing approximately equimolar amounts of free thiols (SH) and thiosulfates (SSO 3 H), a process known as sulfitolysis. Proteins and peptides containing thiosulfates were separated by reverse‐phase high‐performance liquid chromatography (RP‐HPLC) and characterized by mass spectrometry (MS) and peptide mapping. The mass of the thiosulfate‐containing peptide formed from oxidized insulin B chain was 3478.02 Da, 80 Da greater than the reduced peptide and corresponding precisely to addition of sulfur trioxide (SO 3 ). Disulfide bond cleavage was also observed using RP‐HPLC and MS after incubation of the intramolecular homodimer of mouse S100A8 (mass 20614 Da). The mass of HPLC‐separated A8‐SH was 10308 Da, and 10388 Da for A8‐SSO 3 H. Loss of SO 3 from multiply charged precursor ions was generally observed at elevated declustering potentials in the source region or within q 2 at relatively low collision energies (∼20 V). The characteristic loss of SO 3 at low collision energies preceded peptide backbone fragmentations at higher collision energies. Accurate mass measurement and charge‐state discrimination, using a hybrid quadrupole time‐of‐flight mass spectrometer, allowed specific detection of thiosulfate‐containing peptides. An information‐dependent acquisition method, where the switch criterion was loss of m/z 79.9568, specifically identified 11 thiosulfate‐containing peptides using nano‐LC/MS from a tryptic digest of bovine serum albumin (BSA). Copyright © 2005 John Wiley & Sons, Ltd.