How to Reconstitute Lyophilised Peptides

Reconstitution is the point where a stable dry cake becomes a fragile solution. The procedure below is standard laboratory practice for research materials and is written for a bench context only.

Before you open anything

1. 1Let the vial reach room temperature while still sealed — condensation on cold powder introduces water you did not intend.
2. 2Disinfect the stopper and let it dry.
3. 3Check the cake: white to off-white, intact or collapsed is normal; discolouration is not.
4. 4Decide the final concentration and calculate the diluent volume before drawing anything.

Adding the diluent

Angle the needle so the stream runs down the inside wall of the vial rather than directly onto the cake. Add slowly. Peptides are surface-active, and a jet of liquid straight into the powder creates foam, which means denatured material at the air–liquid interface.

Dissolving

Roll the vial gently between your palms, or leave it to stand. Never shake and never vortex a peptide solution unless the documentation explicitly calls for it. Complete dissolution can take several minutes; a faint haze that clears on standing is common, persistent particulates are not.

Solubility problems

• Basic sequences generally dissolve readily in water.
• Acidic sequences may need a small volume of dilute base before dilution.
• Hydrophobic sequences may require an organic co-solvent step, added before aqueous dilution.
• Never force dissolution with heat.

After reconstitution

Label the vial with compound, concentration, diluent and date. Store cold and dark. For longer holds, aliquot into single-use volumes: repeated freeze–thaw cycles are one of the most reliable ways to degrade a peptide solution.