Storage and handling of lyophilised peptides

Peptides are supplied as a lyophilised powder because the dry state is the stable one. Almost everything that degrades a peptide — hydrolysis, oxidation, aggregation, enzymatic attack — needs water, warmth, light or oxygen, and freeze-drying removes the first of those. How the vial is handled between the courier and the bench decides how much of that stability survives.

In transit

Lyophilised peptide tolerates ambient shipping. Several days at room temperature does not meaningfully degrade a dry, sealed vial, which is why cold-chain shipping is not standard for research quantities and why its absence is not a quality signal either way. Arriving warm is normal. Arriving damp is not.

On arrival

Move vials to −20 °C for anything beyond immediate use, kept dark and dry. A domestic freezer is adequate for most sequences; frost-free models cycle through warming phases, so a stable non-cycling freezer is preferable where there is a choice.

The single most common avoidable mistake happens in the first minute: opening a cold vial in a warm room. Air condenses on the cold powder and the vial takes on water before anything else has been done to it. Let a vial reach room temperature fully — sealed — before the stopper is touched. On a small vial that is fifteen to twenty minutes.

Light, moisture and air

Three ordinary precautions cover most of what goes wrong:

• Light. Sequences containing tryptophan or tyrosine are photosensitive. Amber vials or a closed box solve this completely.
• Moisture. Lyophilised material is hygroscopic and will pull water out of room air given the chance. Keep the stopper seated; keep desiccant with long-term stock.
• Oxygen. Methionine, cysteine and tryptophan residues oxidise. Sequences carrying them — MOTS-c has two methionines, for instance — are the ones where sloppy storage shows up first in the chromatogram.

Once in solution

Reconstituted material is a different proposition from dry powder. Water restores every degradation route that lyophilisation shut down, so solutions are held cold, used within a short window and not left at room temperature between uses. Peptides with free cysteine residues can dimerise in solution; several sequences are pH-sensitive, and the buffer chosen at this point matters more than anything done earlier.

Freeze-thaw cycling is the other reliable way to lose material. Each cycle concentrates solutes at the ice boundary and encourages aggregation, and the damage accumulates. Where a solution will be used repeatedly, splitting it into single-use aliquots at the outset costs nothing and removes the problem entirely.

Reading the vial against its certificate

A lyophilised cake should be intact and uniform. A collapsed or melted-looking cake, or a film up the wall of the vial, suggests the vial has been warm at some point — possibly during lyophilisation itself. It is not automatically a quality failure, but it is worth checking against the lot’s certificate and against the other vials in the box.

Colour is a weaker signal than it is usually treated as. Most peptides are white to off-white; copper-containing material such as GHK-Cu is blue by chemistry, not by contamination.

A note on what this page is not

This page covers laboratory storage and handling of reference material. It does not describe preparation for administration to any organism, and no quantity, volume or schedule on this site should be read that way.

Research use only

Everything in this catalog is supplied for in-vitro laboratory research and analytical reference use by qualified professionals. These materials are not drugs, dietary supplements or cosmetics, are not intended for human or veterinary use or for diagnostic purposes, and nothing on this page describes an effect in humans.