How to store lyophilized peptides.
Research peptides ship as a freeze-dried powder because a dry solid is far more stable than the same peptide in water. How you store the vial before and after it goes into solution decides how long the material stays as tested.
Why peptides ship freeze-dried.
Freeze-drying (lyophilization) removes water from a frozen solution and leaves a dry, porous solid, usually seen as a small white cake at the bottom of the vial (more on what a lyophilized peptide is). Reviews of pharmaceutical freeze-drying describe how the dry state slows the chemical and physical reactions that degrade peptides and proteins in solution.
Studies of dried proteins also show that storage stability depends on keeping the solid well below its glass transition temperature, which is one reason warm storage shortens the useful life of a dry peptide.
Storing the sealed vial.
Keep sealed vials at 2 to 8 °C, the condition printed on Helion labels, in a dry place and protected from light. Leave them in the original sealed vial until you need them.
Before opening a cold vial, let it reach room temperature. Opening it cold draws moisture from the air onto the powder, and water is what the freeze-drying removed.
After the peptide is in solution.
In water, peptides become vulnerable to the degradation reactions that dry storage slows: deamidation of asparagine, isomerization of aspartate, oxidation and aggregation. Formulation reviews describe these as the main stability concerns for peptides and proteins in solution.
Once a peptide is in solution, keep it refrigerated at 2 to 8 °C and protected from light, and avoid repeated freeze and thaw cycles. For a vial that will be used over several sessions, the usual laboratory diluent is bacteriostatic water, whose 0.9% benzyl alcohol suppresses microbial growth after the vial is opened. How long a peptide lasts in solution depends on its sequence; the guide to how long peptides last breaks it down by compound.
When an order arrives.
Helion ships dry powder by USPS Priority Mail. Short transit at room temperature is normal for a lyophilized solid; put the vials in the refrigerator when they arrive and check that each lot number matches its Certificate of Analysis.
Storage at a glance.
| Sealed lyophilized vial | 2 to 8 °C, dry, protected from light |
|---|---|
| Opening a cold vial | Let it reach room temperature first |
| Peptide in solution | 2 to 8 °C, protected from light, no repeated freeze and thaw |
| Bacteriostatic water | Sealed, room temperature, away from light |
Specs and storage by compound.
Questions (5)
Do lyophilized peptides need to be refrigerated?
Helion lots are labeled for storage at 2 to 8 °C. Keep sealed vials refrigerated, dry and away from light until use.
Can peptides be frozen?
A sealed lyophilized powder tolerates cold well. Once a peptide is in solution, avoid repeated freeze and thaw cycles, which can promote aggregation.
How long does a peptide last once it is in solution?
It depends on the compound, its concentration and how it is kept. Peptides degrade faster in water than as a dry powder, so keep solutions refrigerated, protected from light and free of repeated freezing.
Why does the powder look like a small cake?
That is the normal appearance of a freeze-dried solid. The cake can look fluffy, compact or slightly cracked; a small amount of powder at the bottom of the vial is expected.
What should I use to bring peptides into solution?
For a vial used over several sessions, the standard laboratory diluent is bacteriostatic water: sterile water with 0.9% benzyl alcohol to suppress microbial growth.
Published studies (4)
- Applications of Freezing and Freeze-Drying in Pharmaceutical Formulations
- Optimizing storage stability of lyophilized recombinant human interleukin-11 with disaccharide/hydroxyethyl starch mixtures
- Formulation considerations for proteins susceptible to asparagine deamidation and aspartate isomerization
- Formulation and stability of cytokine therapeutics
Citations from PubMed for reference. They describe the compound in the literature, not any Helion lot, and nothing here is guidance on use.