3C-O2-1605 PDF
MS2 Analysis of Phosphopeptide by Dinuclear Metal Complex-Aided Electron Transfer Dissociation
Phosphorylation is the most abundant protein modification, and MS2 with electron transfer dissociation (ETD) has proven to be a promising method for phosphoproteomic applications owing to its ability to determine phosphorylation sites on proteins. However, low precursor charge states hinder the ability to obtain useful information through peptide sequencing by ETD, and the presence of acidic phosphate groups contributes to a low charge state of peptide ions. The targeted chemical derivatization of the phosphate groups in phosphopeptides is necessary to promote the wider utility of ETD for large-scale phosphoproteomics. We have previously reported that the use of dinuclear zinc complex named “phostag” for electrospray ionization (ESI) increased the charge state of phosphopeptides and facilitate the backbone cleavage induced by ETD. Although addition of phostag increase the sequence coverage, the phostag-aided ETD led to the dissociation of ligand. The development of new metal complex instead of phostag is necessary to suppress the ligand dissociation and preferential formation of the fragment due to N–Cα bond cleavage. In this study, we synthetized the dimetallic complex, which selectively bound to phosphate group and facilitate the N-Cα bond cleavage by ETD. The detailed process of ETD is discussed using DFT with NM15/LanL2DZ/6-31G(d) level calculation.