FIGURE 2.

MALDI-TOF MS of petunia leaf and root extracts reveals putative cyclotide masses. Following reduction of disulfide bonds, free thiols were alkylated, and peptide backbones were enzymatically digested with endoproteinase Glu-C. A, native leaf extract. B, reduced and carbamidomethylated leaf extract. C, reduced, carbamidomethylated, and enzymatically digested leaf extract. D, native root extract. E, reduced and carbamidomethylated root extract. F, reduced, carbamidomethylated, and enzymatically digested root extract. G, the structures of native, alkylated, and digested Phyb A (peak a) and Phyb M (peak b) are schematically represented beside their corresponding spectra.