Phosphoproteomics of HeLa cells Using Protea’s TiO2 SpinTip Sample Prep Kit and LC-ESI-MS/MS

In this application note, more than 700 unique phosphorylation sites were identified from a HeLa cell lysate using a single TiO2 SpinTip for selective enrichment. Phosphorylated amino acids exist at a low natural stoichiometry, requiring the use of selective enrichment strategies for the concentration of phosphorylated peptides and proteins prior to analysis, usually by mass spectrometry. The buffer system developed allows for preferential binding of phosphopeptides to titanium dioxide compared to non-phosphorylated peptides with acidic residues.