Reconstitution & Storage Best Practices
Step-by-step guidance on reconstituting lyophilised peptides, choosing the right solvent, and storing compounds to preserve stability and potency.
Most research peptides are supplied as lyophilised (freeze-dried) powders. Before use in an experiment, they must be reconstituted — dissolved in an appropriate solvent to create a stock solution. Correct reconstitution and storage practices are critical to preserving compound integrity and ensuring reproducible experimental results.
Why peptides are supplied lyophilised
Lyophilisation removes water from the peptide solution under vacuum at low temperature, leaving a dry powder that is stable at low temperatures for extended periods. In this form, peptides are far less susceptible to hydrolysis, oxidation, and microbial degradation than they would be in solution. The lyophilised form also simplifies shipping and storage logistics. Once reconstituted, however, the clock starts — solutions are generally less stable than powders and should be used promptly or stored under appropriate conditions.
Choosing the right solvent
Solvent selection depends on the physicochemical properties of the specific peptide — primarily its sequence, charge, and hydrophobicity. As a general starting point: water or aqueous buffers (PBS, HEPES) work well for hydrophilic peptides; a small amount of acetic acid (0.1–1%) aids dissolution of basic peptides (those rich in Arg, Lys, His); trifluoroethanol (TFE) or DMSO can be used for hydrophobic peptides, typically followed by dilution into aqueous buffer. Always consult the product documentation or contact the supplier if you are unsure which solvent is appropriate for a specific compound.
Reconstitution protocol
Allow the vial to equilibrate to room temperature before opening to prevent condensation on the powder. Add solvent slowly to the side of the vial rather than directly onto the powder. Gently swirl or vortex — do not sonicate unless necessary, as this can cause aggregation or degradation. If the peptide does not dissolve readily, try warming briefly to 37°C or adding a small volume of an organic co-solvent before diluting with aqueous buffer. Prepare stock solutions at a higher concentration than your working concentration to minimise the number of freeze-thaw cycles.
Storage of lyophilised powder
Unopened lyophilised peptides should be stored at -20°C or below, away from light and moisture. Desiccant sachets in the storage container help maintain a dry environment. Avoid repeated temperature cycling. Before opening a vial that has been stored at low temperature, allow it to equilibrate to room temperature in a sealed container to prevent moisture absorption from condensation.
Storage of reconstituted solutions
Once reconstituted, peptide solutions are best stored at -80°C for long-term stability, or at -20°C for shorter periods. Prepare single-use aliquots to avoid repeated freeze-thaw cycles, which can cause aggregation and degradation. Label each aliquot with the compound name, concentration, solvent, date of preparation, and batch number. Most reconstituted peptide solutions should be used within 3–6 months when stored at -20°C, though this varies by compound. Avoid storing solutions at 4°C for more than a few days.
Signs of degradation
Visual inspection is a simple first check: a solution that has become cloudy, discoloured, or shows visible particulates may have degraded or aggregated. However, degradation is not always visible — if you observe unexpected results in your assay, consider whether compound quality could be a contributing factor. When in doubt, prepare a fresh stock from a new aliquot or a new vial.