Figure 3
LC-MS analysis revealed the N-terminal sequence of erythrocyte frataxin. (a) Chromatograms of the unique N-terminal AspN peptide from erythrocyte frataxin. Top panel: doubly charged ion of the intact peptide (MH22+); bottom panel: triply charged ion of the intact peptide (MH33+). The MS signal intensities are shown on the right (5.1 × 106, 5.3 × 107). (b) Product ion spectrum of the N-terminal peptide of frataxin isoform E obtained from erythrocytes by AspN digestion. The b- and y-ions are labeled on the peptide and spectrum. (c) A diagram showing the amino acids present in the full length (precursor) frataxin, mature form (81–210) and erythrocyte frataxin (isoform E, 76–201).
