What MOTS-c is
MOTS-c is a peptide of sixteen amino acid residues. What makes it unusual among research peptides is where its sequence comes from: it is encoded not in nuclear DNA but within the mitochondrial genome, in a short open reading frame inside the 12S ribosomal RNA region. Peptides of this origin are described in the literature as mitochondrially derived, and MOTS-c is the most studied of them.
The sequence, in single-letter notation, is MRWQEMGYIFYPRKLR. The material supplied for laboratory work is made by solid-phase synthesis, so its documentation looks like that of any other synthetic peptide: a synthesis record, a chromatographic purity determination, and an identity confirmation.
| Property | Value | Where it is confirmed |
|---|---|---|
| Residue count | 16 | Synthesis record |
| Sequence | MRWQEMGYIFYPRKLR | Synthesis record; identity result |
| Approximate mass | near 2,174 g/mol | Certificate of analysis |
| Origin of sequence | Mitochondrial 12S rRNA reading frame | Published literature |
| Physical form supplied | Lyophilized solid | Label and batch record |
Why oxidation is this peptide's failure mode
Read the sequence again and count the methionines. There are two — at position one and position six — and there is a tryptophan at position three. Those three residues are the most oxidation-prone side chains in ordinary peptide chemistry, and having three of them in the first six positions tells you most of what you need to know about how this material degrades.
This is a useful contrast with BPC-157, whose sequence contains neither methionine nor cysteine and whose degradation is therefore driven by a backbone rearrangement rather than by oxidation. Two peptides, two entirely different things to watch for, both readable straight off the sequence before any instrument is involved.
What that means on a report:
- Oxidised methionine adds 16 mass units. A single oxidation event produces a species 16 heavier than the parent, and a second produces one 32 heavier. Where identity is reported by mass, these are resolvable directly — the oxidised species is a distinct, identifiable number rather than a vague concern.
- Oxidised species elute earlier. Oxidation makes a peptide more polar, so on a reversed-phase column the oxidised form comes off before the parent. A shoulder or a small peak on the early side of the main peak is the expected signature, not a random anomaly.
- Tryptophan degrades in more than one way. Its indole ring is sensitive to both oxidation and light, and its breakdown products are less predictable than a methionine sulfoxide. A chromatogram with several small early peaks is more consistent with tryptophan chemistry than with synthesis impurities.
Identity and purity on the report
Purity and identity answer separate questions. Purity is established by reversed-phase HPLC: everything reaching the detector is integrated, and the purity figure is the main peak's area as a percentage of the total. Identity is established either by mass agreement against the calculated value or by retention-time matching against a reference standard run under the same method, the latter stated as HPLC-RTM on a certificate.
For an oxidation-prone sequence the chromatogram carries more weight than usual. A purity figure records the state of one sample on one day; the pattern of early-eluting peaks records whether the material has begun to oxidise. A report that gives a number without the plot behind it cannot be checked. See how to read an HPLC chromatogram.
Storage of the lyophilized solid
Freeze-drying removes the water that drives most degradation, which is why the material ships as a sealed solid rather than in solution. Three conditions matter for a vial in storage, and for this sequence the third is not optional.
- Temperature. Colder storage slows every chemical process available to the peptide; long-term stock is generally held frozen.
- Moisture. A lyophilized peptide is hygroscopic. A vial brought from cold storage into a warm room and opened before it has equilibrated will condense atmospheric water into the solid, and that adsorbed water is what lets chemistry proceed in something that looks dry.
- Air and light. Oxidation needs oxygen, and tryptophan is additionally light-sensitive. For this sequence, an intact seal and opaque storage are doing real work rather than being generic good practice.
Stability is documented, not assumed: a laboratory establishes it by holding material under defined conditions and re-analysing at intervals. Storing lyophilized research materials covers the general case.
What the published literature covers
The research record is preclinical and comparatively recent, the compound having been described in the literature only in the last decade. Published work is dominated by cell-culture systems and rodent models, with reported areas of investigation including metabolic regulation, mitochondrial signalling, and exercise-response models. Because the field is young, the volume of independent replication is smaller than for longer-studied peptides, which is a reasonable thing to weigh when reading it.
The compound has not completed the regulatory process that would establish safety or efficacy for any medical indication, and findings in rodent and cell-culture models do not transfer automatically to other species. Arctic Lab Supply does not publish research conclusions, recommend applications, or provide guidance on experimental design.