Reconstituting a Peptide

  • Bring frozen or refrigerated peptides to room temperature in a desiccated chamber to avoid water absorption.
  • Always begin by reconstituting a small amount of peptide before committing the entire lot.
  • Use sterile water or sterile filtration.  If there are any Methionine (M), Cysteine (C), or Tryptophan (W) residues, use oxygen free solvents to prevent oxidation. 
  • Avoid reconstituting a peptide in a buffer, such as PBS.  Salts hinder solubility.
  • Choose the appropriate solvent.  Begin reconstituting at a concentration higher than your desired final working concentration.


Amino Acid Characteristics

Recommended Solvent

Hydrophilic residues (KRHDEN)


Hydrophobic residues (AVLIMFW)

Low solubility in aqueous solvents; are soluble in organic solvents (DMF, DMSO, TFA, Acetonitrile)


  • A solubilized peptide is completely clear. No flecks or cloudiness should be present.
  • If a peptide with more hydrophilic residues is still not completely reconstituted:
    • Adjust the pH of the solution according to the overall charge of the peptide
      • Count the possible POSITIVE charges (K, R, H, and free N-terminus)
      • Count the possible NEGATIVE charges (D, E, and free C-terminus)
      • Determine which is greater.
        • If positive charges are greater, add dilute acid dropwise to proteinate residues and maximize charge.
        • If negative charges are greater, add dilute base dropwise to deproteinate and maximize charge.
        • try sonication, gentle heat or an organic solvent, such as DMSO, Acetonitrile or DMF.

If your peptide is still not completely reconstituted, lyophilize the peptide and begin again.