Selective Exploration of Protein Phosphorylation, Glycosylation and Disulfide Bridges by Mass-Pair Detection

摘要

Post-translational modifications (PTMs) modulate the activity of proteins in cells. Analysis of these PTMs presents immense challenges, but their identification has engendered essential knowledge of biological functions. In this study, we developed a novel method, termed Mass Pair Detection (MPD), for selectively targeting phosphopeptides, glycopeptides or disulfide bridge peptides, in either an LTQ-Orbitrap mass spectrometer or a MALID-TOF/TOF mass spectrometer. The characteristic peak pair of masses can originate from neutral loss of phosphoric acid or of monosaccharide residues, or it can be generated by enzymatic labeling of modified peptides. Only paired peaks are selected for CID MS/MS to obtain sequence information about the modified peptides, so as to increase detection sensitivity.