On-plate enrichment methods for MALDI-MS analysis in proteomics

As one of the most comprehensive and versatile tools for investigating proteomics, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) still faces the problem of identification of low abundant proteins and post-translational modifications (PTMs) of proteins. These proteins typically require concentration and isolation prior to MS analysis. The surfaces of MALDI targets have been modified so they can be used not only as sample supports but as functional substrates for sample enrichment. These modified targets are therefore capable of concentrating and binding molecules of interest selectively from sample solutions placed on them. In this report, current on-plate techniques employed for enrichment of low-abundance proteins, including those for selective capture of phosphopeptides and glycopeptides prior to MALDI-MS analysis, were reviewed.