PNNL

Abstract

Two dimensional liquid chromatography (2D LC) is commonly used for shotgun proteomics to improve the analysis dynamic range. Reversed phase liquid chromatography (RPLC) has been routinely employed as the second dimensional separation prior to the mass spectrometric analysis. Construction of 2D separation with RP-RP arises a concern for the separation orthogonality. In this study, we applied a novel concatenation strategy to improve the orthogonality of 2D RP-RP formed by low pH (i.e., pH 3) and high pH (i.e., pH 10) RPLC. We confidently identified 3753 proteins (18570 unique peptides) and 5907 proteins (37633 unique peptides) from low pH RPLC-RP and high pH RPLC-RP, respectively, for a trypsin-digested human MCF10A cell sample. Compared with SCX-RP, the high pH-low pH RP-RP approach resulted in 1.8-fold and 1.6-fold in the number of peptide and protein identifications, respectively. In addition to the broader identifications, the High pH-low pH RP-RP approach has advantages including the improved protein sequence coverage, the simplified sample processing, and the reduced sample loss. These results demonstrated that the concatenation high pH-low pH RP-RP strategy is an attractive alternative to SCX for 2D LC shotgun proteomic analysis.