Proper peptide storage is crucial to maintaining their integrity and ensuring reliable lab results. Poor storage can lead to contamination, oxidation, and degradation, making your peptides and experiments ineffective. While some peptides are more stable than others, following best practices can extend their shelf life regardless of composition.
Temperature Control and Light Exposure
Once peptides arrive, it’s essential to keep them cool and shielded from light. Here’s a breakdown based on usage timelines:
- Short-term storage (days to a few months): Refrigerate peptides at 4°C (39°F). Lyophilized peptides can remain stable at room temperature for a few weeks if needed.
- Long-term storage (several months to years): Freeze peptides at -80°C (-112°F). This prevents degradation and maintains stability over extended periods.
It’s equally important to avoid repeated freeze-thaw cycles, as these can increase susceptibility to degradation. Additionally, frost-free freezers should be avoided due to temperature fluctuations during defrosting cycles.
Preventing Oxidation and Moisture Contamination
Exposure to air and moisture can degrade peptides. Here are some preventive measures:
- Moisture Control: Allow frozen peptides to reach room temperature before opening the container to prevent condensation from forming on the cold surface.
- Minimize Air Exposure: Keep containers sealed as much as possible. When resealing, use dry, inert gas (such as nitrogen or argon) to reduce the risk of oxidation.
Certain amino acids, like cysteine (C), methionine (M), and tryptophan (W), are particularly prone to oxidation. To further minimize degradation, many researchers aliquot peptides into separate vials to avoid frequent handling and thawing.
Storing Peptides in Solution
Peptides in solution are much less stable than their lyophilized counterparts and are also vulnerable to bacterial degradation. Peptides with sequences containing Cys, Met, Trp, Asp, Gln, and N-terminal Glu degrade more rapidly in solution.
If peptides must be stored in solution, use sterile buffers with a pH between 5 and 6. Additionally, divide the solution into aliquots to minimize freeze-thaw cycles. Refrigerated peptide solutions (at 4°C) can remain stable for up to 30 days, though freezing is recommended for peptides that degrade easily.
Choosing the Right Storage Containers
The right container is critical for proper peptide storage. Containers should be clean, clear (or translucent), and resistant to chemical reactions. Both glass and plastic vials are commonly used:
- Glass: High-quality glass vials provide durability and chemical resistance.
- Plastic: Polystyrene vials are clear but not chemically resistant, while polypropylene vials are chemically resistant but translucent.
Peptides may be shipped in plastic to reduce the risk of breakage but can be transferred to glass containers if preferred.
General Peptide Storage Tips
To maintain peptide stability and performance, follow these general guidelines:
- Store peptides in a cool, dry, and dark place.
- Avoid repeated freeze-thaw cycles.
- Minimize exposure to air.
- Keep peptides away from light.
- Avoid storing peptides in solution for extended periods.
- Aliquot peptides based on experimental needs to reduce handling.
By implementing these best practices, you can preserve your peptides’ integrity and ensure successful laboratory experiments.
