Limit freeze-thaw events and use proper aliquoting to keep peptide samples functional in the lab
Repeated freezing and thawing can cause peptide aggregation, oxidation and loss of activity. Ice crystal formation disrupts the three dimensional structure and can expose sensitive residues to hydrolysis. Even a few cycles may reduce assay reproducibility, so it is worth planning how to avoid them.
The most reliable way to protect a stock is to divide it into single-use aliquots shortly after reconstitution. Use low-binding microcentrifuge tubes or cryovials, and work quickly to keep the solution on ice. Aliquots should be sized for the typical volume needed in an experiment, with a small excess to account for pipetting loss.
Store aliquots at the temperature recommended by the peptide manufacturer, usually -20 °C or -80 °C. Keep the freezer door closed as much as possible and avoid placing tubes near the door where temperature fluctuations are greatest. Label each tube with peptide name, concentration, date of preparation and an identifier for the aliquot number.
Record each freeze-thaw event in a lab notebook or electronic log. If a sample has been thawed more than once, discard it and prepare a fresh aliquot. Maintaining this simple documentation helps you track sample history and ensures consistent experimental results.
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