Lyophilized peptides generally have excellent stabilities (in most cases, can be stored for years at -20ºC or lower temperatures with little or no degradation), but, in solution, they generally have much more limited stabilities. Since peptides are susceptible to degradation by proteases of bacterial or microbial origin, the first rule is to prepare sterile solutions, either by peptide reconstitution in sterile, distilled water, or by sterile filtration after reconstitution. For peptides which contain methionine, cystenic or tryptophan residues, oxidation may generate impurities with or without concomitant biological inactivation. To avoid this, peptides containing these amino acids should be dissolved in oxygen-free solvents.
For purity standards, Southern Research Company cold packs each research peptide order free of charge.