MALDI identification of human apolipoprotein A-I. MALDI MS-MS data confirms the identification of the 24.7 kDa biomarker to be a fragment of human APOA1. (A) MS Reflector Positive spectrum obtained from the in-gel trypsin digestion of the ~25 kDa band cut out from fraction 3 shows the precursor peaks generated by trypsin. (B) ProteinPilot MS-MS data shows that 8 peptides were sequenced and matched to human APOA1 with more than 95% confidence. (C) MS-MS sequence coverage. Peptides sequenced with more than 95% confidence (green) or less 95% confidence (red) together covered 47.7% of the full-length APOA1 human protein sequence.