Manual and Automated Solid Phase Synthesis of Peptides for Breast Cancer Cell Targeting

Four peptides were synthesized using solid phase peptide synthesis. The two target peptides synthesized were based off peptide 18-4 and its negative analog. Each were synthesized once manually, and once using an automatic peptide synthesizer. Peptide 18-4 has a high affinity for breast cancer cells, allowing it to be used to detect circulating tumor cells (CTCs) in blood (Kaur et. al, 2015). Manual solid phase peptide synthesis is performed by anchoring the first amino acid to Wang resin and coupling each Fmoc protected amino acid individually until the target sequence is achieved. To synthesize the peptides automatically, the automated Tribute Synthesizer was used. To analyze the success of the peptide synthesis, mass spectrometry was used to determine if the synthesized peptide has the correct molecular mass. Reversed Phase-High Performance Liquid Chromatography (RP-HPLC) was used to analyze the relative amount of the correct peptide in the synthesized sample. Due to greater potential for human error, the two peptides synthesized manually were missing one or two amino acids. Using the Tribute synthesizer, peptide 18-4 and its negative analog were successfully synthesized. Automated peptide synthesis was found to be faster and more successful than manual peptide synthesis