MOTS-c shelf life is longest when the freeze-dried powder stays sealed, dry, dark and cold. Its two methionines and one tryptophan make oxidation the main way it breaks down, and that change leaves no visible sign. Let a cold vial warm before opening it, and treat the certificate as the only source of a date.
- MOTS-c (Human) is a 16-residue linear peptide, MRWQEMGYIFYPRKLR, with an average mass near 2174.6 Da and no cysteine or disulfide.
- Oxidation of Met1, Met6 and Trp3 is the characteristic degradation route, which makes light and oxygen exclusion the controls that matter most.
- The sequence contains no asparagine, so the fast classical deamidation route is absent and only Gln4 is a slow deamidation candidate.
- A net charge of roughly plus four drives adsorption onto glass,, so it binds readily to glass surfaces.
- Letting a sealed vial reach room temperature before opening prevents the condensation uptake that is the most common avoidable handling error.
- No MOTS-c medicine is approved anywhere and no compendial monograph exists, so the lot certificate of analysis is the only specification available.
What in the MOTS-c sequence sets its shelf life?
Think of it like a bag of ground coffee. Sealed, cool and dry, it keeps for a long time, but once air gets at it the quality starts to fade. For this peptide, air goes after the methionine and tryptophan residues first.
MOTS-c (Human) is a short linear peptide, sixteen residues, sequence MRWQEMGYIFYPRKLR. It was described by Lee and colleagues in Cell Metabolism in 2015 as a mitochondrial-derived peptide encoded within an open reading frame in the 12S rRNA region of mitochondrial DNA. Average mass calculated from the sequence is close to 2174.6 Da for the unmodified free-acid form, which is what most research-grade material is.
Read the sequence before reading any storage advice. Position by position: Met1, Arg2, Trp3, Gln4, Glu5, Met6, Gly7, Tyr8, Ile9, Phe10, Tyr11, Pro12, Arg13, Lys14, Leu15, Arg16. Four things follow from that list, and they set the whole handling picture.
There is no cysteine, so there is no disulfide to scramble and no thiol to oxidize into a dimer. There is no asparagine, so the fast classical deamidation route that dominates so many peptide stability discussions is absent; Gln4 can deamidate, but glutamine does so an order of magnitude more slowly than asparagine in most sequence contexts. There are two methionines and a tryptophan, which makes oxidation the characteristic degradation route for this molecule. And with three arginines plus a lysine against a single glutamate, the peptide carries a strong net positive charge at neutral pH, which matters for how it behaves on glass and on chromatography columns.
The molecule is also unlipidated and short. That makes it far less interface-active than the fatty-acylated peptides whose handling guidance dominates the field, and correspondingly less prone to the aggregation failures those molecules show. Different chemistry, different worry list.
- Oxygen and light — sulfoxide formation at Met1 and Met6, ring damage at Trp3
- Moisture — condensation into a cold vial opened too soon
- Adsorption — cationic peptide binding to glass at low concentration
- Temperature — a rate modifier for every route above
- Time: the certificate is the only document entitled to carry a date
Which degradation routes apply, and where?
| Route | Site in this sequence | What drives it | Practical control |
|---|---|---|---|
| Methionine oxidation to sulfoxide | Met1, Met6 | Headspace oxygen, trace metals, peroxide impurities | Sealed vial, minimal headspace, cold |
| Tryptophan photo-oxidation and ring cleavage | Trp3 | Light, especially near-UV; oxygen | Amber glass or opaque secondary container |
| Tyrosine oxidation | Tyr8, Tyr11 | Light, oxidants, metal ions | Same controls as above |
| Deamidation | Gln4 | Water, temperature, pH above roughly 6 | Dry solid storage |
| Backbone hydrolysis | Any amide bond; Asp-free sequence is comparatively slow | Water activity, temperature, extremes of pH | Keep the solid dry and desiccated |
The reason to write the table this way rather than copying a generic peptide list is that generic lists lead people to spend their attention on the wrong variable. For a lipidated 39-mer, agitation and interfaces are the story. For MOTS-c, oxygen and light are. The review by Butreddy and colleagues on lyophilized protein and peptide instability sets out the mechanisms in more depth and remains a fair map of the territory.
How should a sealed vial be handled before opening?
Most avoidable loss in a peptide laboratory happens in the first minute a vial is open, and it happens because the glass was cold. A vial taken from a −20 °C freezer into a room at 22 °C and 55% relative humidity is far below the dew point. Break the seal at that moment and water condenses onto the cake immediately. Lyophilized material is hygroscopic and takes it up without any visible change.
The control costs twenty to thirty minutes and no money: let the sealed vial equilibrate to room temperature on the bench before the seal is broken, every time. No exceptions for being behind schedule. Then work quickly, reseal, and return the vial to storage with a desiccant.
Two smaller points that belong in the same habit. First, centrifuge or tap the vial down before opening. Fine lyophilizate migrates into the stopper and cap threads in transit, and material lost to the closure is material that never reaches the experiment. Second, inspect the cake and record what you see. A fine white cake or a thin film both look normal for a milligram-scale fill. A collapsed, glassy, or visibly moist cake is a different observation and worth writing down on receipt.
How to store MOTS-c, step by step
- Hold unopened stock as sealed powder at −20 °C or colder, desiccated and dark.
- Before opening, let the sealed vial reach room temperature on the bench; twenty to thirty minutes covers it.
- Tap or spin the vial down, then inspect the cake and record what you see.
- Work quickly, reseal, and return the vial to storage with a desiccant.
- Label every vial with the source lot and the date it was first opened.
What MOTS-c storage conditions suit each physical state?
| State | Temperature | Light | Relative horizon | Why |
|---|---|---|---|---|
| Sealed powder, unopened stock | −20 °C or colder, desiccated | Dark | Longest | Oxidation, deamidation and hydrolysis all slowed; water excluded |
| Sealed powder, in-use vial | 2 to 8 °C, desiccated | Dark | Shorter | Acceptable where the vial is consumed inside a defined window |
| Powder in transit | Ambient | Dark, insulated | Days | Dry solid tolerates short excursions |
The horizons stay relative on purpose. A specific shelf life belongs to a lot that has been through a stability study in that container under those conditions, which is what ICH Q1A(R2) describes for regulated products and what almost no research-grade peptide has behind it. If a supplier prints a confident month count with no supporting data, they are quoting a convention. The lot's certificate of analysis is the only document entitled to carry a date, and where it carries none, the honest statement in your own record is that the window is unestablished. Our own position on what a certificate should contain is set out in the quality standard.
How do you detect degradation rather than assume it?
Storage discussions tend to stop at prevention. The analytical half matters as much, because a laboratory that cannot see degradation has no way to know whether its handling works.
Reversed-phase HPLC on a C18 column with a water/acetonitrile gradient and 0.1% trifluoroacetic acid resolves MOTS-c comfortably. Detection at 280 nm is available thanks to Trp3 and the two tyrosines, which is convenient: the same chromophores that make the peptide oxidation-prone also make it easy to quantify. Purity by area percentage against a reference injection of the same lot is the routine check. USP general chapter <621> sets the system-suitability expectations any method should meet before its numbers are trusted.
Oxidation has a characteristic chromatographic signature. Methionine sulfoxide is more polar than methionine, so oxidized species elute earlier than the parent peak, typically as one or two shoulders or resolved peaks just ahead of it. Under LC-MS the confirmation is unambiguous:
| Observed shift | Interpretation | Note |
|---|---|---|
| +16 Da | Single methionine sulfoxide | Two sites available, so +32 Da is possible |
| +32 Da | Two sulfoxides, or one sulfone | MS/MS localization distinguishes them |
| +4, +16, +32 Da on Trp | Tryptophan oxidation products | Kynurenine and hydroxytryptophan among them |
| +0.98 Da | Deamidation | Gln4 is the only candidate here |
| +18 Da fragments | Backbone hydrolysis | Look for lower-mass fragment pairs |
A useful discipline: run the purity check when a lot arrives and again before the lot is used up. Two data points on the same lot, in your own hands, tell you more about your storage practice than any published shelf life.
What should the record say?
Storage discipline that is not written down is not reproducible. For a MOTS-c lot the minimum record is the source lot identifier, the certificate it maps to, the cake's appearance on receipt, the storage temperature, the date each vial was first opened, and the initials of whoever opened it.
One correction catches people: the mass on the label is usually gross peptide, and the material also carries counterion and residual water. A trifluoroacetate or acetate salt with a peptide content in the mid-eighties by percentage holds meaningfully less free peptide than the nominal figure.
The reason is diagnostic. When an assay comes out wrong, the first question is whether the material was what the protocol assumed. A record that traces the vial back to the lot and the certificate answers that in a minute. Log freezer excursions too, including the ordinary ones, so that a suspect result can be checked against a real temperature history rather than against memory. The guide on tirzepatide storage and stability applies the same record habits to other materials.
What is the regulatory position?
MOTS-c is an endogenous mitochondrial-derived peptide that has been studied in cell and animal models since its description in 2015. No medicine containing MOTS-c has been approved by FDA, EMA or any comparable regulator, and we are aware of no USP or Ph. Eur. monograph for the peptide. Two consequences follow for a laboratory. There is no compendial reference standard against which identity and purity can be established, so a supplier's own reference injection and its analytical methods are the whole basis of any purity claim. And there is no regulatory-defined attribute set, which means the certificate of analysis is the only specification in existence for that lot.
Prohibited-substance lists in competitive sport are revised annually and are written in categories as well as by name. Anyone with an obligation under one of them should read the current list text directly rather than rely on a secondary summary, including this one.
Status verified August 26, 2026.
FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. NOT FOR PERSONAL, MEDICAL, DIAGNOSTIC, THERAPEUTIC, OR RECREATIONAL USE.
Bottom line
MOTS-c shelf life comes down to oxygen, light and water. The two methionines and the tryptophan oxidize without any visible sign, so keep the powder sealed, dark and cold, let it warm before opening. No lot has a shelf life beyond what its certificate supports, and your own purity checks on arrival and later tell you whether the handling works.
Common questions
What is the shelf life of MOTS-c?
Does lyophilized MOTS-c need to be frozen?
Why is oxidation the main concern for this peptide rather than hydrolysis?
Can I see oxidation in the vial?
More handling guides
Sources
- Lee et al., Cell Metabolism, 2015. Original description of MOTS-c as a 16-residue peptide encoded within the mitochondrial 12S rRNA region; supports the sequence, length and identity statements.
- Butreddy et al., International Journal of Biological Macromolecules, 2020. Review of degradation stresses, stabilization mechanisms and analytical techniques for lyophilized peptide and protein products; supports the degradation-route table and the primacy of dry solid-state storage.
- USP General Chapter <621>, Chromatography. Establishes system-suitability requirements for the reversed-phase HPLC purity methods that any peptide purity figure should be able to meet.
- ICH Q1A(R2), Stability Testing of New Drug Substances and Products. Defines what a stability study must comprise before a shelf life can be assigned; supports the position that a research-grade lot without such data has an unestablished window.
