9 min read · updated 2026-07-08
Peptide Storage and Stability: A Laboratory Reference
Temperature, light, moisture, and freeze-thaw — what actually degrades peptide material and what the data shows.
Lyophilised versus reconstituted
Lyophilised peptide is substantially more stable than peptide in solution, because most degradation pathways require water. The practical consequence is that material should be held lyophilised for as long as possible and reconstituted only in the quantity needed. Sequence-specific stability data appears on the lot certificate; general guidance is a starting point, not a substitute for it.
The principal degradation pathways
Oxidation affects methionine, cysteine, and tryptophan, and is accelerated by light, dissolved oxygen, and trace metals. Deamidation of asparagine and glutamine is pH-dependent and proceeds fastest in neutral to alkaline conditions, with Asn-Gly sequences particularly susceptible. Hydrolysis is most likely at aspartic acid residues, especially Asp-Pro bonds. Aggregation is concentration-dependent and is the pathway most affected by freeze-thaw cycling. Which of these matters for a given peptide is determined by its sequence — this is why storage guidance cannot be generic.
Freeze-thaw and aliquoting
Each freeze-thaw cycle exposes the peptide to a concentration gradient at the ice front and to mechanical stress, both of which promote aggregation. Aliquoting reconstituted stock into single-use volumes at the point of first reconstitution eliminates repeated cycling. This is the single most effective handling change for maintaining solution stability, and it costs nothing.
Light, containers, and buffers
Peptides containing tryptophan, tyrosine, or phenylalanine are photosensitive; amber vials or foil wrapping addresses this. Peptides can adsorb onto glass and some plastics at low concentration, causing real losses in dilute solutions — low-binding polypropylene mitigates this. Buffer selection matters for deamidation-prone sequences, since the reaction rate is strongly pH-dependent.
Frequently asked
How long is lyophilised peptide stable at −20 °C?
Sequence-dependent. Many peptides are stable for extended periods under proper lyophilised storage, but the reliable figure is the stability data on the specific lot certificate rather than a general rule.
Does bacteriostatic water extend solution stability?
Bacteriostatic water contains benzyl alcohol, which inhibits microbial growth. It addresses contamination, not chemical degradation — oxidation, deamidation, and hydrolysis proceed regardless.
Why does aliquoting matter more than storage temperature for solutions?
Because freeze-thaw cycling drives aggregation through mechanical and concentration stress. A well-aliquoted stock frozen once outperforms a single tube frozen and thawed repeatedly, even at the same temperature.
See the practice, not just the principle
Every lot we release is published in full — assay, method, specification, and measured result — including lots that have sold out.
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