Fig. 4
Mass spectra of the native and acrolein-modified Aß1-16. The ion density (y-axis) was plotted against m/z ratio (x-axis). The b-ions (blue peaks) represent N-terminal fragments, whereas y-ions (red peaks) represents C-terminal fragments. Acrolein-modified histidine and lysine were pointed with arrows. A Native Aß1-16 peptide. B Acrolein-modified Aß1-16 at H6, H13, H14 or K16. Only the selected spectra were shown