Storing lyophilized peptides: a lab guide
Most peptide degradation in the lab isn’t dramatic. It happens slowly, through moisture, oxidation and repeated freeze-thaw cycles, and shows up as inconsistent results months later. Good storage habits prevent most of it.
Why lyophilized peptides are stable
Lyophilization removes water by freezing the peptide solution and then sublimating the ice under vacuum. Without water, the main degradation reactions, hydrolysis and deamidation, slow dramatically. Sealed and frozen, a lyophilized peptide can stay within specification for years.
The three enemies: water, oxygen and temperature swings
- Water drives hydrolysis of peptide bonds and deamidation of asparagine and glutamine. Lyophilized powder is hygroscopic, so it pulls moisture from the air whenever a cold vial is opened.
- Oxygen oxidises methionine, cysteine and tryptophan residues. Sealing under nitrogen and minimising headspace both help.
- Freeze-thaw cycles concentrate solutes as ice forms and can cause aggregation. Each cycle does a little damage.
Practical storage rules
- Store sealed vials at −20 °C, or −80 °C for long-term storage, away from light.
- Warm vials to room temperature before opening so condensation can’t form on the powder.
- Reconstitute only what you need, and divide stock solutions into single-use aliquots.
- Freeze aliquots at −20 °C or below and never refreeze a thawed aliquot.
- Record the batch number, solvent, concentration and date on every aliquot.
Sequence matters
Some sequences need extra care. Peptides with free cysteines can form unwanted disulfides in solution; those with N-terminal glutamine can cyclise to pyroglutamate; and asparagine followed by glycine deamidates especially quickly. Check your compound’s sequence and the literature before planning long experiments.
Our full Storage & Handling guide covers solvent choice, shelf life and disposal.