When weighing out a quantity of peptide, warm the package as noted above and perform the measurement as quickly as possible. Store all unused peptide at -20°C or less. Sequences containing cysteine, methionine, tryptophan, asparagine, glutamine, or N-terminal glutamic acid will have shorter shelf lives than other peptides.
Lyophilized peptides should be stored in a sealed container with desiccant at -80°C (at least -20°C) in order to minimize peptide degradation. The peptide can be stored for several years under these conditions, which also prevent bacterial degradation, secondary structure formation, and oxidation.