Figure 4
MS analysis of tryptic recombinant pINSL3. (A) Total ion chromatogram of tryptic-digested recombinant pINSL3 fragments displayed major peaks at 18.7 and 32.3 min (marked I and II) for non-reduced form and at 17.4 and 41.4 min (marked III and IV) for reduced form. (B) MS1 survey spectra of these marked peaks (I–IV) highlighted the cysteine peptide precursor ions. Based on accurate masses of the observed peptides, the peak I indicates that two peptides P1 (L13CGHHFVR20) and P2 (H94CCLSGCTR102) are connected by two disulfide bonds. The peak II implies that two peptides P3 (L25CGGPR30) and P4 (Q103DLLTLCPH111) are linked by a disulfide bond. Peaks III and IV suggest peptide P1 and P2, respectively.
