Baseline Resolution of Isobaric Phosphorylated and Sulfated Peptides and Nucleotides by Electrospray Ionization FTICR MS:  Another Step toward Mass Spectrometry-Based Proteomics

A novel mass spectrometric method to distinguish isobaric monosaccharides that are phosphorylated or sulfated using ion-pairing reagents

“…This work complements other mass spectrometric studies that have discriminated phosphorylation from sulfation using FTICR-MS [1,2], and most recently MALDI-MS, in which the differentiation was accomplished by monitoring the differences in the ionization behavior between the two functional groups [24]. In addition to discriminating these isobars, ion pairing has the added advantage of simultaneously enhancing the mass spectral signal of these acidic groups, even when they are present in complex mixtures of other compounds [20].…”

“…This is the first study demonstrating that ion-pairing can be used for the detection of phosphorylated compounds and the first study to use ion-pairing in conjunction with MS/MS to obtain structural information about the analytes. ( [2][3][4]. They are also involved in glycolysis processes in the extracellular matrix [7,8].…”

“…Phosphorylation is linked to signal transduction, gene expression, cell cycle, cytoskeletal regulation, and apoptosis [1][2][3][4][5][6][7][8]. In particular, phosphorylated carbohydrates are integral components of nucleic acids [1,5], oligosaccharides [1,5], glycopeptides [2][3][4]6], and glycoproteins [2][3][4].…”

“…Recent MS experiments to identify phosphorylated compounds include exact mass differentiation [2] and discrimination using ionmolecule reactions [1] by using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). While these two methods are useful in differentiating the presence of phosphorylated and sulfated compounds, only a few groups have access to these sophisticated instruments.…”

Distinguishing phosphorylation and sulfation in carbohydrates and glycoproteins using ion-pairing and mass spectrometry

“…High-resolution MS methods, such as Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), have been used to distinguish between phosphorylated and sulfated compounds based on their slight difference in mass [19] or by their ability to react differently in ion-molecule reactions [20]. Other MS methods, such as matrix-assisted laser desorption/ionization (MALDI) [21] and electrospray ionization (ESI) [22], have been recently reported to distinguish phosphorylation and sulfation.…”