Applications of MALDI-MS in Proteomics

Similarly, phosphatases are used to detect and identify phosphopeptides in MALDl-MS. Phosphatase treatment leads to a mass decrease of 80 Da for phosphopeptides [7, 50-52]. 

In proteome studies, the process usually begins with a highly complex mixture of proteins, typically hundreds of unknown species. This requires one or several protein fractionation steps such as 1-D or 2-D gel electrophoresis or LC separation of the proteins and peptides prior to MALDI-MS analysis. The different types of fractionation methods can be combined in several ways for example, SDS-PAGE followed by LC separation of in-gel-digested peptides. In contrast to ESI, LC-separation techniques cannot be directly coupled to the MALDI instruments. Instead, the LC-separated peptide or protein fractions are spotted onto the MALDI-target, and then analyzed in an offline approach. 

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