FIG. 1.
MS/MS product ion spectra from doubly charged precursor ions at m/z 653.8, a naturally processed HLA class II peptide identified as SAGKVSSTLASELG from the nucleoprotein of MV (A), and products of m/z 653.8 from the synthesized peptide SAGKVSSTLASELG (B). The naturally processed spectrum was generated by gas-phase fractionation in conjunction with two-dimensional LC-MS/MS. The synthesized peptide was analyzed by one-dimensional nano-LC-MS/MS. The Sequest scoring parameters XCorr and ΔCn are shown and are described in the text.