Phosphopeptide enrichment and analysis using a combination of metal oxide affinity purification and LC MALDI MS
In this study we have evaluated a new way of enriching phosphopeptides by using a metal oxide based solid phase extraction (SPE) micro scale device. This sorbent has a high affinity for phosphopeptides and the problem of acidic adsorption is greatly minimized. Furthermore, recent developments in MALDI and LC-MALDI spotting devices, allow the coupling of the off-line chromatographic separation step to the subsequent MS analysis. This approach has been compared to a homemade microcolumn desalting approach on protein digest mixtures.