Peptide Stability

Oxidation (methionine, cysteine, tryptophan side chains), hydrolysis (peptide bond cleavage in aqueous solution), aggregation (intermolecular contacts especially in hydrophobic peptides), and adsorption to glass or plastic surfaces.

Lower temperature, lower pH variability, absence of light, absence of oxygen, and absence of repeated mechanical stress (shaking, freeze/thaw) all extend usable shelf-life.

Lyophilised at -20°C: 24+ months. Reconstituted at 2–8°C: 4–8 weeks for most peptides. Refer to the COA's stability section for compound-specific data.

Stability studies track how a compound's measured purity changes over time under defined conditions — temperature, humidity, light, and the physical state (powder versus solution). The output is a degradation curve, not a single number: a sequence that loses 0.1% purity per month refrigerated as powder may lose that much in days once reconstituted and left at room temperature.

This is why stability claims should always name their conditions. 'Stable for two years' is meaningless without 'lyophilised, sealed, −20°C, protected from light'. The same compound can be excellent archival material and fragile bench material, depending entirely on which of those phrases applies.

Not all sequences age equally. Motifs containing methionine or cysteine oxidise; asparagine and glutamine deamidate over time, subtly changing mass and behaviour; sequences prone to aggregation lose effective concentration as material falls out of solution. Proline-rich and highly charged sequences tend to be the most forgiving.

Knowing a sequence's weak point converts stability from an abstraction into a handling decision: an oxidation-sensitive compound earns an argon headspace or minimal air exposure; an aggregation-prone one earns prompt use after reconstitution. The product's reference literature usually signals which class it falls into — and the certificate's water content is the single best proxy for how the powder was handled at the finish line.