Strong cation-exchange chromatography protein separation

In the gel-free approaches, also referred as shotgun proteomics, proteins in a mixture are digested and the peptides released separated by reverse-phase HPLC, either alone or combined with strong cation exchange chromatography... 

Figure 4.8. MuDPIT platform. The MuDPIT or multidimensional gel protein identification system is an multidimensional liquid chromatography (LC)-based system of separation prior to tandem mass spectrometry (MS/MS). It is not necessary to purify proteins prior MuDPIT, although a reduction in protein complexity by some prior purification is helpful in obtaining interpretable spectra. Protein lysates are digested into peptides that are loaded onto a strong cation exchange (SCX) support. Peptides are sequentially eluted onto a reverse-phase column for a second separation. Eluted peptides from the reverse-phase column are electrosprayed into a tandem mass spectrometer for amino acid sequencing and identification of proteins in the sample.

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