The short answer
MOTS-c is a 16-residue mitochondrial-derived peptide of roughly 2,175 Da. Because it contains two methionine residues and a tryptophan, oxidised species appearing as +16 Da satellite peaks are an expected degradation signature on mass spectra, and should be read as oxidation rather than as evidence of a wrong sequence.
A peptide encoded inside the mitochondrial genome
MOTS-c is a 16-amino-acid peptide encoded by a short open reading frame within the mitochondrial 12S rRNA gene — one of a small group of mitochondrial-derived peptides identified over the last decade. It was first reported in 2015 in work describing effects on the folate cycle and downstream AMPK activation.
Research interest sits in metabolic regulation, skeletal muscle bioenergetics and ageing biology. The evidence base is overwhelmingly preclinical: cell lines, rodent models, and observational measurement of the peptide in human plasma rather than interventional human trials of the peptide itself.
MOTS-c is not an approved drug and is supplied strictly as a laboratory research material.
Why +16 Da peaks appear, and what they mean
The MOTS-c sequence contains two methionine residues and a tryptophan. All three are oxidation-prone, and oxidation adds sixteen daltons per oxygen atom incorporated. The practical consequence on a mass spectrum is satellite peaks at +16 Da, and sometimes +32 Da where two sites have oxidised.
This is a degradation signature, not a different molecule. Reading it correctly matters in both directions: a certificate showing modest oxidised species is describing a real and expected property of this peptide, while someone unfamiliar with the sequence might mistake those peaks for evidence of a wrong or contaminated product.
It also has a handling implication. Oxidation is influenced by storage, light and time in solution, so a re-test of reconstituted material some weeks later may not reproduce the original figure — a general truth for peptides that is particularly visible here.
What to confirm on a MOTS-c certificate
Confirm the intact mass sits near 2,175 Da for the 16-residue sequence, and that identity was determined analytically rather than assumed. Where oxidised species are reported, read them as related substances against a specification, in the way USP ⟨1503⟩ frames related-substance reporting for synthetic peptides.
Read purity as a method-bound figure with the wavelength and specification stated, and check net peptide content where reported, since salt counterion and residual water contribute to powder mass.
Then apply the standard checks that are independent of which peptide is in the vial: the lot on the certificate matches the lot on the vial, contamination controls are present, and the document can be verified with the laboratory that issued it.
The oxidation sensitivity carries a handling consequence that outlasts the certificate. Because the relevant residues oxidise on exposure to air, light and time in solution, the condition of the material at the bench is a function of storage as much as of manufacture. A certificate describes the powder as it was analysed; it cannot describe what happened afterwards. Laboratories working with this peptide generally treat reconstitution as the start of a clock rather than a neutral step, and record their own conditions accordingly — which is the only way the analytical figure and the working material stay connected.
Questions researchers ask
What molecular weight should MOTS-c show on a COA?
Approximately 2,175 Da for the 16-residue sequence. Satellite peaks at +16 Da or +32 Da are consistent with oxidation of the peptide's methionine and tryptophan residues rather than with a different molecule being present.
Why does my MOTS-c mass spec show a +16 peak?
Oxidation. The sequence contains two methionines and a tryptophan, and each oxygen incorporated adds sixteen daltons. A modest oxidised fraction is an expected degradation signature for this peptide and is reported as a related substance, not as a separate compound.
Does MOTS-c purity change after reconstitution?
It can. Oxidation is influenced by storage conditions, light exposure and time in solution, so material re-tested weeks after reconstitution may not reproduce the certificate figure. Certificates describe the lyophilised powder as analysed at the laboratory.
Is MOTS-c an approved drug?
No. The published evidence is predominantly preclinical — cell and rodent models, plus observational human plasma measurements — and MOTS-c is not approved in any jurisdiction. It is supplied for laboratory research use only.
At a glance
- Class
- 16-residue mitochondrial-derived peptide (encoded in mitochondrial 12S rRNA)
- Expected mass
- ≈ 2,175 Da
- Expected artifact
- +16 Da / +32 Da oxidation peaks (2× Met, 1× Trp)
- Evidence base
- Predominantly preclinical — cell and rodent models
- Status
- Research use only — not an approved drug
How our MOTS-c lots test
Applying the same standard described above to our own material. Each certificate below opens on the issuing laboratory's portal— not a PDF hosted here — so you are reading the lab's record, not ours.
Sources
Written from primary literature and published standards — never from other suppliers' marketing copy.
- PubChem CID 146675088 — MOTS-c, formula, mass and sequence ↗
- Lee C et al., Cell Metab 2015 — the mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis ↗
- MOTS-c: a promising mitochondrial-derived peptide (PMC review) ↗
- USP General Chapter ⟨1503⟩ Quality Attributes of Synthetic Peptide Drug Substances ↗
Written by Ivory Science. Scientific review: pending appointment of a named reviewer. Until then this page cites its sources directly so every claim can be checked at origin.
Related notes
For research use only. Not for human or veterinary use, ingestion or administration. Nothing here is medical advice, and no statement on this page has been evaluated by the FDA. MOTS-c is not an approved medicine.