Figure 4.

Mass spectrometry analysis of Juruin peptides. (A) Collision-induced dissociation spectrum from mass/charge (m/z) 1211.3 generated by trypsin digestion after analysis by LC/MS, showing the dominant fragment KIDCS with a m/z of 621.26, which corresponds to an N-terminal segment. (B) Collision-induced dissociation spectrum from m/z 2579.8, showing the b and y ion series that corresponds to the partial sequencing of the tryptic peptide between residues Phe¹ to Lys³⁰, which allowed the assignment of four cysteines, Cys³, Cys⁷, Cys²⁴, and Cys³⁰, as well as the lysine rich region Lys²²-Lys²³. (C) MS/MS spectrum from the precursor ion at m/z 1679.69 which corresponds to the C-terminus of Juruin, lacking the amidated valine at the end.