Lyophilised peptides are stable materials when stored correctly and surprisingly fragile when they are not. Four things degrade them: heat, moisture, light and repeated freeze–thaw. Handling comes down to controlling those four.
Lyophilised powder
Sealed, dry and cold is the whole recipe. As a general working standard:
- −20 °C for routine storage; −80 °C for long-term archival
- Sealed, in the original vial, with the desiccant if supplied
- Protected from light — particularly for sequences containing tryptophan, tyrosine, cysteine or methionine, which are the residues most prone to photo-oxidation
Short excursions to room temperature during shipping are normal and are not the same as prolonged warm storage. Lyophilised material is shipped without cold chain routinely.
Let it warm before you open it
This is the step most often skipped. Opening a vial straight from −20 °C lets warm room air condense moisture directly onto cold powder. Water is the enemy of a lyophilised cake, and you have just added some.
Bring the sealed vial to room temperature first — 20 to 30 minutes on the bench — then open it.
After reconstitution
A peptide in solution is a different stability proposition entirely. Hydrolysis, oxidation and aggregation all proceed in ways they simply do not in a dry cake.
- Store at 2–8 °C and use within the working period your laboratory has established for that material
- Aliquot if the solution will be accessed more than a few times — this is the single highest-value habit in peptide handling
- Avoid repeated freeze–thaw cycles; each one costs material to aggregation
- Keep solutions out of light
Sequence-specific vulnerabilities
Not every peptide degrades the same way. Broadly:
- Cysteine-containing sequences can form unwanted disulfide bridges; oxygen exposure matters more for these.
- Methionine and tryptophan are the residues most readily oxidised.
- Asparagine and glutamine are prone to deamidation, which is accelerated at higher pH.
- Copper complexes such as GHK-Cu are supplied as a coloured complex; colour variation between lots is normal and is not by itself an indicator of purity.
A workable default
If you want one protocol that covers most materials: keep the powder sealed at −20 °C in the dark, warm sealed vials to room temperature before opening, reconstitute gently down the vial wall, aliquot immediately, and hold working aliquots at 2–8 °C.
Every Aegis Bio compound page carries the storage and handling notes for that material alongside its available specifications.