Peptide Reconstitution Guidelines
Generally, it is advised to first attempt to dissolve peptides in solvents that are easy to remove by lyophilization. This is a precaution: in case the initial solvent is not effective, it can be removed again by the lyophilization process. Typically, the researcher should first attempt to dissolve the peptide in sterile distilled water or regular bacteriostatic water or in sterile dilute acetic acid (0.1%) solution. As a general guideline, it is recommended to test a small portion of the peptide for solubility in the chosen solvent before attempting to dissolve the entire peptide.
Importantly, the initial use of sterile water (or dilute acetic acid) will allow the researcher to dry the peptide without any unwanted residues in case the peptide fails to dissolve. Once the initial ineffective solvent is removed, the researcher can then attempt to dissolve the peptide in increasingly stronger solvents.
Additionally, researchers should dissolve the peptide in a sterile solvent to give a stock solution that is 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 very difficult to recover the peptide unadulterated. However, the peptide can always be diluted further with the assay buffer later on.
In the laboratory, sonication can be tried as method 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 sonication 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 type of surface scum. If so, it is likely that the peptide is only suspended in the solution, not dissolved; therefore, a stronger solvent will probably be required.