Fig. 2. Enrichment of phosphopeptides using hydroxy acid-modified metal oxide chromatography (HAMMOC).
A metal oxide chromatography tip is prepared by packing bulk-titania beads into a C8-membrane StageTip.25) Tryptic digests of the cell lysate are loaded onto the tip in the presence of a 300 mg/mL lactic acid. After washing twice, phosphopeptides are eluted using an aqueous base solution such as 0.5% piperidine. The fractionation with a successive elution improved the number of identified phosphopeptides in the following LC-MS/MS analysis.76,77)
