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Everything you need to know about reconstituting Peptides

All Peptides we sell are supplied in a lyophilized (freeze-dried) powder form, which is perfect for transporting the Peptides. We do not provide Peptides pre-mixed, and we wouldn't recommend that you purchase them in such a way as they will heavily degrade while in transport.

What is Lyophilization?

Lyophilization is a process in which water is removed from a compound after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapour without passing through a liquid phase.

Lyophilized peptides commonly resemble a small white “puck” that may have a fluffy or more granular appearance. Different lyophilization techniques can yield a more voluminous (fluffy) or compacted (granular) lyophilized peptide.

Before lyophilized peptides can be utilized, they must be reconstituted; that is, they must be dissolved in a liquid solution. Unfortunately, no “one size fits all” solvent will solubilize all peptides while maintaining peptide integrity and compatibility with biological assays. While sterile, distilled water, or regular bacteriostatic water is the first choice, this will not dissolve all peptides. As a result, the researcher may undertake a trial-and-error approach and attempt to dissolve in increasingly stronger solvents. 

Sodium Chloride water is NOT recommended due to its tendency to cause precipitates with acetate salts.

What should you use to reconstitute a Peptide?

We recommend starting with Bacteriostatic water additionally, for Peptides that are struggling to fully dilute, we would then look at acetic acid. For hydrophobic peptides, use a 50% aqueous acetic acid.

Additionally, researchers should dissolve the peptide in a sterile solvent to give a stock solution at a higher concentration than required for the assay. If the assay buffer is used first and the peptide does not dissolve, it can be challenging to recover the peptide unadulterated. However, the peptide can be diluted further with the assay buffer later.

Practical Implementation

Although some peptides will need a more potent solvent to dissolve fully in a solution, as discussed above, bacteriostatic water is adequate in many cases and is the most common solvent or diluent for reconstituting a peptide. 

*Important: allow the peptide to come to room temperature before opening.

You may also choose to pass your peptide solution through a 0.2 µm filter if bacterial contamination is a concern.

Example using sterile bacteriostatic water as the diluent:

  • Step 1 – Remove the plastic cap from the peptide vial to expose the rubber stopper.
  • Step 2 – Remove the plastic cap from the sterile water vial to expose the rubber stopper.
  • Step 3 – To prevent bacterial contamination, swab the rubber stoppers with alcohol.
  • Step 4 – Extract the required mL (millilitres) of water from the bacteriostatic vial.
  • Step 5 – Insert the required mL (millilitres) of bacteriostatic water into the peptide vial, letting the water slowly enter the vial.
  • Step 6 – Gently swirl the solution until all peptide is dissolved – do not shake the vial.


In the laboratory, sonication can be tried to improve the rate of peptide dissolution in the solvent if the peptide continues to persist as visible particles in the solution. Sonication will not change the peptide’s solubility characteristics in a given solvent; the process merely assists with breaking down lumps of solid peptide and briskly stirring the solution. After the sonication process, the researcher should examine the solution to see if it is cloudy, has gelled, or has any surface scum. If so, the peptide is likely only suspended in the solution, not dissolved; therefore, a more potent solvent will probably be required.

What you need to know about peptide storage

  1. Peptides are sensitive to temperature and humidity. Peptides can degrade or denature if exposed to extreme temperatures or fluctuations in humidity. It's vital to store peptides in a cool, dry place to minimize these risks.
  2. Peptides should be stored in the fridge or freezer. To ensure the stability of your peptides, it's best to keep them in the refrigerator (2-8°C) or freezer (-20°C). Avoid storing peptides in the fridge or freezer door, as this is the warmest area.
  3. Peptides should be protected from light. Peptides can be sensitive to light, especially UV radiation. It's a good idea to store peptides in dark places or containers that block light.
  4. Peptides should be handled carefully. Peptides can be damaged by rough handling or exposure to contaminants. Be sure to take your peptides carefully and use clean utensils and containers.