Molecular Biotechnology Core

Frequently Asked Questions

What modifications are available for synthetic peptides?

The most common modification performed during peptide synthesis are incorporation of stable isotopes (15N and 13C), D-amino acids, non-protein amino acids, azido group, phospho-Tyr, phospho-Ser/Thr, Thr- & Ser-glycosyl, biotinylation at N- or C- terminals, fatty acid conjugation, fluorochrome conjugation, N-acetylation, peptides amides, and peptide cyclization via s-s bonds and many other modifications.

How do you perform the quality analysis of peptides?

An analytical-scale reverse-phase HPLC chromatography and the mass analysis by MALDI-TOF-TOF mass spectrometry are performed for every peptide to ensure the highest quality of synthetic product.

How do I store my peptide?

Peptides are provided as lyophilized product that should be stored as dry powder at -20°C to -80°C in a desiccator, if possible. After lyophilization, peptides retain significant amounts of water. Peptides are slowly degraded particularly the cysteine-containing peptides are oxidized over time at -20°C. Some key information about peptides:

  • Some peptides are very hygroscopic and peptides also contain counter-ions that are paired with charged residues (e.g., acetate or trifluoroacetate for positively charged residues).
  • The peptide solution should be stored at -20°C in small aliquots.
  • Pass the peptide solution through a sterile filter before storing to prevent bacterial contamination
  • Maintain peptide in an oxygen-f environment as peptides having cysteine, methionine, trypophan, glutamine, and asparagine residues are susceptible to oxidation and have reduced self-life.

How do I reconstitute my peptides?

The vial or tube containing peptide should be allowed to warm to room temperature in a desiccator containing fresh desiccant before opening. The best solvent to reconstitute the peptide is DMF (up to 30%), added drop wise until the peptide dissolves.

What is MAP (Multiple Antigen Peptide)?

The MAP system utilizes a peptidyl core of th or seven radially branched lysine residues, on to which the peptide sequence of interest can be built using standard solid-phase chemistry. The lysine core yields the MAP bearing four or eight copies of the peptide epitope (high molar ratio), depending on the inner core that generally accounts for less than 10% of total molecular weight. The MAP system does not require a carrier protein for conjugation. The high molar ratio and dense packing of multiple copies of the antigenic epitope in a MAP has been shown to produce strong immunogenic response.