HPLC-MS conditions for peptide purity analysis

All peptides were assessed for purity by analytical C18 RP-HP-LCMS prior to use in biological assays. Buffers used were 0.1% trifluoroacetic acid in water (A) and 0.1% trifluoroacetic acid in acetonitrile (B). The standard method (1) consisted of a linear gradient of 5% to 95% B over 10 minutes on Agilent 1100 series HPLC-MSD and method (2) consisted of a linear gradient of 5% to 95% B over 8 minutes on Waters 2767 series HPLC-MSD. The C18 column (Phenomenex, Luna C18, 4.6 × 150mm) effluent was immediately mass analyzed in electrospray positive mode. Accurate mass measurements of final peptides were performed using C18 reversed-phase chromatography mass spectrometry (RPHPLCMS) and mass detected on a Waters Synapt G2 Q-Tof mass spectrometer tuned to a resolution (FWHM) of 25,000. Exact intact masses were calculated based on the monoisotopic m/z value of the base peak charge state. All peptides were analyzed using these methods. Supporting data of peptide 45 is shown (Supplementary Figure S2) as representative data sets of the all the molecules investigated (characterization of all peptides presented on Table 1S).