Lyophilized (freeze-dried) peptides are hygroscopic — they absorb moisture from ambient air — and degrade through oxidation, hydrolysis, and aggregation when stored improperly. Understanding the degradation pathways and recommended storage conditions is essential for preserving research compound integrity.
Shelf Life by Storage Condition
| Form | Temperature | Shelf Life |
|---|---|---|
| Lyophilized (unopened) | -20°C freezer | 2–3 years |
| Lyophilized (unopened) | 2–8°C refrigerator | 12–18 months |
| Lyophilized (unopened) | Room temp (dark) | 3–6 months |
| Reconstituted (bac water) | 2–8°C refrigerator | ~30 days |
| Raw bulk powder | -20°C (inert gas sealed) | 3–5 years |
The Three Enemies of Peptide Stability
1. Moisture. Even trace water can hydrolyze peptide bonds. Store vials with desiccant packs in airtight containers. Let frozen vials equilibrate to room temperature before opening — cold glass condenses atmospheric moisture instantly.
2. Temperature fluctuation. Household refrigerator-freezers with automatic defrost cycles create temperature swings of ±5°C multiple times per day. A dedicated laboratory freezer without auto-defrost is ideal for long-term storage.
3. Light. UV radiation accelerates oxidation of methionine, tryptophan, and cysteine residues. Amber glass vials provide protection; clear vials should be wrapped in foil or stored in opaque containers.
Avoiding Freeze-Thaw Damage
Each freeze-thaw cycle causes microscopic ice crystal formation that can damage peptide structure. Key practices:
- Aliquot bulk powder into single-use portions at the time of first opening
- Never re-freeze a vial that has been brought to room temperature
- Store lyophilized peptides in the freezer and reconstituted peptides in the refrigerator — never freeze reconstituted solutions
For research use only. Not for human consumption.