Peptide Synthesis

For each protein to be quantified, we synthesize minimally two tryptic peptides(25 µM small scale fmoc using the Yale WM Keck Small Peptide Synthesis Resource). Briefly, each peptide is isotopically labeled by incorporating 15N/13C to one amino acid residue, typically Val, Phe, Arg, Ile, or Leu near the C-terminus. After instrument cleavage of the peptide from the resin, crude peptides are purified by reverse phase HPLC and analyzed by MALDI-MS (Applied Biosystems 4800 MALDI-Tof/Tof). The synthesized peptides are tracked using our YPED Synthetic Peptide Database, with a library of peptides being built up.