Fragmentation spectrum of the HBHA154LVGIELPGKAEAAGK168peptide with post-translational modification. Shown is a spectrum obtained by nanoLC-MS/MS analysis with HCD fragmentation mode using LTQ Velos Orbitrap mass spectrometer. The precursor ion had an m/z 733.93 in charge state 2. The peptide sequence was obtained by all y ions (y1 to y14) and 5 consecutive b ions (b2 to b6). Moreover, the Δm = +14 Da on the K*168 indicated the presence of a methylation.