Peptide Storage and Shelf Life: The Laboratory Guide

Peptides degrade by four principal chemical routes, and three of them need water as a reactant or a mobility medium.

• ·Hydrolysis. Peptide bond cleavage, requiring water. Effectively stopped in a dry solid.
• ·Deamidation. Conversion of asparagine and glutamine side chains to the corresponding acids, proceeding through a cyclic imide intermediate. Strongly water- and pH-dependent, and among the best-characterized solid-state degradation routes.[2]
• ·Oxidation. Methionine, cysteine and tryptophan side chains oxidising on exposure to air and light. This is the one route that proceeds meaningfully in the dry state, which is why lyophilized vials are sealed under partial vacuum or inert gas.
• ·Aggregation. Physical rather than chemical: chains associating into species that will not redissolve. Driven by concentration, agitation and freeze-thaw cycling.
• ·A fifth route worth naming for lyophilized material specifically: residual moisture in the cake enables amide-linked adduct formation with excipients, which is why moisture control in the dry state matters more than it intuitively should.[1]

• ·-20 °C for long-term storage. The standard for research peptides. Colder is not meaningfully better for most sequences and adds handling risk.
• ·Dark. Tryptophan and tyrosine absorb in the near-UV, and copper complexes such as GHK-Cu are more light-sensitive than plain peptides.
• ·Dry. Keep the vial sealed. Every opening admits humid air, and the desiccant in a shipping container is not a substitute for an intact seal.
• ·Room temperature to open. Always let a frozen vial equilibrate before breaking the seal, or condensate goes into the cake.
• ·In transit. Short ambient shipping is generally tolerated by lyophilized peptides. It is the reason material ships dry rather than in solution.

Freeze-thaw cycling deserves its own note. Each cycle concentrates solutes at the ice front, drives local pH shifts as buffer components crystallize at different rates, and creates ice-water interfaces at which peptides denature. The loss is cumulative: five cycles is not one cycle five times, it is worse.

• ·2 to 8 °C, refrigerated. Not frozen unless the protocol specifically calls for it and the solution is aliquoted.
• ·Protected from light. Amber vials or foil.
• ·Aliquoted. This is the single most useful habit. Divide into single-use volumes on the day of reconstitution so no aliquot is ever thawed twice.
• ·Used within the window your protocol defines. Solution stability is sequence-specific and no general number is honest across a whole catalogue.

• ·Methionine-containing peptides. MOTS-c has two methionines. Each oxidized residue adds 16 Da, visible on a mass-spectrometry report as a satellite species. Minimize air exposure.
• ·Asn and Gln-rich sequences. Most exposed to deamidation, and the effect is pH-sensitive in solution.
• ·Aggregation-prone classes. Amylin analogues descend from a hormone whose native form aggregates into amyloid fibrils. Handle gently, avoid agitation, avoid repeated freezing.
• ·Copper complexes. GHK-Cu is more light-sensitive than a plain peptide, and the metal centre adds a route that a peptide-only stability discussion does not cover.
• ·Small molecules. NAD+ is markedly hygroscopic and less stable in solution than most peptides. 5-Amino-1MQ is a quaternary salt and also hygroscopic, though generally more robust than a peptide once dry.

A certificate reports what a laboratory measured on a given date. It is not a prediction about the future, and no supplier in this market runs the formal stability programme that would be needed to assign a real expiry date.

What a batch record does provide is a starting point: material tested at high purity and correct content on a known date, stored correctly from then on, is in a knowable condition. Material with no certificate and no batch code has no starting point at all, which is why the storage question and the verification question are the same question asked at different times.

Published Certificate

Select strength

10mg20mg40mg45mg

Batch

MOTS-CA-26F-10

Purity (HPLC)

98.683%

Measured content

11.20 mglabelled 10 mg

Laboratory

Janoshik

Verify on the lab’s own databaseAll published certificates

• ·Lyophilized: -20 °C, dark, dry, sealed, equilibrate to room temperature before opening.
• ·Reconstituted: 2 to 8 °C, dark, aliquoted, used within your protocol's window.
• ·Never freeze-thaw the same aliquot repeatedly.
• ·Swirl, never shake. Foam is lost material.
• ·Methionine-containing and copper-complexed compounds need more care than the rest.