Peptides degrade by predictable routes: hydrolysis, oxidation, aggregation and adsorption to container surfaces. Storage practice is mostly a matter of slowing all four.
Lyophilized material
Dry peptide is the stable form, and the goal is to keep it dry and cold.
- Temperature. -20 °C is the usual specification for long-term storage. Some materials tolerate 2-8 °C for shorter periods; a few specify below -18 °C. Each product page and COA gives the figure for that compound.
- Moisture. Lyophilized cake is hygroscopic. Keep vials sealed and desiccated, and always warm a vial to room temperature before opening so condensation does not form inside it.
- Light. Peptides containing tryptophan, tyrosine, methionine or cysteine are the most light-sensitive. Amber vials or an opaque box handle this.
- Air. Methionine and cysteine residues oxidise. Where a supplier specifies an inert atmosphere, that is why.
Reconstituted material
Once in solution, the clock speeds up considerably.
- 2-8 °C for short-term working storage, protected from light.
- -20 °C in single-use aliquots for anything longer.
- Minimise freeze-thaw. Every cycle costs material to aggregation and adsorption. Aliquot once, at the point of reconstitution, rather than repeatedly thawing a single tube.
- Mind the container. Peptides adsorb to glass and to some plastics, which matters most at low concentrations. Low-bind tubes exist for this reason.
A workable routine
- On arrival, check the vial and transfer it to the storage condition on the COA immediately.
- Record the lot number against the COA before the box goes in the bin.
- Warm to room temperature, sealed, before opening.
- Reconstitute, then aliquot in the same session.
- Label every aliquot with compound, lot, concentration and date — on the tube itself, not the rack.
- Return everything to storage promptly.
Signs something has gone wrong
Cloudiness or visible particulate in a solution that was clear, a cake that has collapsed to a sticky film rather than a dry solid, or discolouration are all reasons to stop and re-evaluate rather than proceed. Aggregation is not always visible, which is the argument for aliquoting rather than relying on inspection.
Related
See how to reconstitute lyophilized peptides and how to read a Certificate of Analysis.
This article covers laboratory handling practice only. All materials supplied by Never Enough Labs are for in-vitro research use by qualified persons 21 years of age or older. Nothing here is medical, veterinary or diagnostic guidance, and no product described is intended for human or animal use.