FIGURE 2. Characterization of the novel cyclotide caripe 1 from Carapichea ipecacuanha.
The MALDI-MS (A) and RP-HPLC trace (B) of Carapichea ipecacuanha is shown. The putative cyclotide mass of 3268.3 Da was selected as precursor for MS/MS experiments (C). The reduced and alkylated (R1A) (D), and endoproteinase GluC digested (E) extract is shown. MALDI-TOF/TOF sequencing of the precursor masses 3634.9 Da (F) and 2814.9 Da (G) from an endoproteinase GluC and a trypsin digest, respectively, allowed the characterization of the novel cyclotide caripe 1 based on observed b- and y-ions. All shown masses are monoisotopic. MS evidence for the existence of cyclotides in all other positive cyclotide plants can be found in the Supporting Information section (Figures S1-S9).