Peptide Synthesis

For each protein to be quantified, we synthesize minimally two tryptic peptides(25 ┬ÁM 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.