Figure 1

MS/MS spectra of representative semi-tryptic and tryptic peptides. iTRAQ reporter ion region and peptide sequencing region of the MS/MS spectrum for semitryptic peptides derived from (A) sulfated glycoprotein 1 (437–443) and (C) α₁-macroglobulin (807–818). Representative tryptic peptides changes are shown for (B) sulfated glycoprotein 1(232–241) and (D) α₁-macroglobulin (1187–1201). Peptide sequences were deduced from the MS/MS spectra based on the observation of continuous series of either N-terminal (b-series) or C-terminal (y-series) ions. The peak areas of iTRAQ quantification (shown in insets of A, B, C, D) ions, m/z 114–117 were used to measure the relative abundance of individual peptides.