Metal-oxide enrichment and gas-phase characterization of sulfopeptides using Fourier transform ion cyclotron resonance mass spectrometry

摘要: Though not as well studied phosphopeptides, sulfopeptides are important for many biological processes, including proper endocrine function and extracellular signaling. The discovery of dates back to the 1920s; however, their enrichment characterization have only recently become broader interest. With a limited toolbox analyzing sulfopeptides, we employ several chemistries develop robust methods. At heart each method lies Fourier transform ion cyclotron resonance mass spectrometry, gas-phase detection with power differentiate even slightest differences, such phosphate vs. sulfonate. First, Lewis acid-base characteristics inherent transition metal oxides examined selective interaction in presence mixtures competing poly-oxyanions. Careful control binding elution pH an optimized amount sulfopeptide loaded onto oxide surface can enhance selectivity up 97% relative abundance compared low 4% prior enrichment. Second, utility activation methods structural is investigated. sulfonate post-translational modification (PTM) extremely labile at pH, high temperature, during gaseous collisional activation. This fragility has challenged researchers discover new techniques analysis intact sulfonated biomolecules. As 2011, authors accepted that lost spectrometric analysis. We found combination different elucidate sequence while keeping residue intact, allowing unambiguous localization this PTM. In particular, negative electron capture dissociation was yield >50% fragmentation efficiency complete retention. Finally, ideas explored improving detachment dissociation, which commonly leads extensive neutral loss from carboxylic acids, precluding efficient backbone subsequent elucidation. To block carbon dioxide loss, chemical derivatization anion adduction were employed. chloride acidic peptides improves provides nearly coverage peptides. addition, N-acetylation shown alter observed pathways, presumably through changes peptide structures.