Generally, lyophilized peptides can be stored long-term in a dry and tightly closed vial at -20°C, and be protected from intense sunlight:
For short-term storage ranging from one week to two months, lyophilized peptides may be stored at 4C.
For long-term storage, lyophilized peptides should be stored at -20C or deep freezer.
Even though this condition keeps most peptides stable for several years, peptides' long-term stability is at risk when peptides expose to moisture, therefore, the vial should be tightly capped at all times. This also requires careful experiment planning to minimize vial openings.
Peptides containing fluorophores should be kept in the dark. Repeated freeze-thaw cycles should be avoided. Before opening, the vial should be allowed to reach ambient temperature in a desiccator. The shelf life of peptide solutions is limited, a peptide solution once prepared should be used as soon as possible.
Peptide Solutions Storage Guideline:
Do not store excessive peptides in solution because the shelf life of peptides in solution is very limited, much shorter than lyophilized peptides. This is especially true for peptides whose sequences contain cysteine, methionine, tryptophan, asparagine and glutamine. It is necessary to aliquot the amount of peptide you need for the day and re-lyophilize the remaining peptide solution. Another drawback is that peptides stored in solution are susceptible to bacterial degradation. If storage of peptide in solution is unavoidable, use sterile buffers at pH 5-6 and store aliquots at -20 degree; and pass the peptide solution through a 0.2 µM filter to rid the bacteria. The peptide powder can be stored at room temperature for 1 week. But if the sequence contains M, W, or C, it can not be stored at room temp.
