MOTS-c is an abbreviation, not a chemical name. What follows is an identity reference for MOTS-c: what the sequence is, what mass to expect, how it behaves under reverse-phase HPLC, and how a buyer can confirm that the material in a vial is what the label says. It leaves aside any question of what MOTS-c does, and preparation, handling and dosing are not covered.
The sequence behind MOTS-c
MOTS-c is a 16-residue linear peptide with the sequence Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg, written in one-letter code as MRWQEMGYIFYPRKLR. All sixteen residues are standard L-amino acids. The common synthetic form has a free N-terminal amine and a free C-terminal acid, with no terminal capping.
The molecular formula is C101H152N28O22S2 and the average molecular mass is approximately 2174.6 g/mol. The two sulfur atoms come from the two methionines, a detail that matters for the impurity profile discussed below.
What the name MOTS-c refers to
MOTS-c stands for mitochondrial open reading frame of the 12S rRNA-c. The sequence is encoded by a short open reading frame within the mitochondrial gene for 12S ribosomal RNA (MT-RNR1), rather than in the nuclear genome, which is why it is grouped with the so-called mitochondrially derived peptides. The name records where the sequence was found in the genome; it is a label for a location, not a description of any property.
As with every compound in this series, the name on a label does not guarantee the molecule in the vial. A 16-mer has many opportunities for a truncated or substituted sequence to be sold under the same designation. The one-letter sequence printed alongside the mass is what identifies the compound, and a supplier should print both. Because the sequence contains no cysteine, there are no disulfide bonds to form or verify: the synthetic material is a single linear chain, and its identity rests entirely on sequence and mass.
How MOTS-c behaves on reverse-phase HPLC
MOTS-c has a mixed character. Four of its sixteen residues are basic (three arginines and one lysine) against a single glutamic acid, so it carries a clear net positive charge at the acidic pH of a standard trifluoroacetic acid mobile phase. At the same time it contains a cluster of hydrophobic and aromatic residues: tryptophan, two tyrosines, phenylalanine, isoleucine, leucine and two methionines. The result is a peptide that retains well on a C18 column and elutes in the middle part of a typical water/acetonitrile gradient, well clear of the solvent front.
The aromatic content also makes the detection choice easy. With one tryptophan and two tyrosines, MOTS-c absorbs usefully at 280 nm as well as on the peptide bond at 214 nm. Reporting both traces is good practice: impurities without aromatic residues show at 214 nm but not at 280 nm, so comparing the two helps tell sequence-related impurities apart from non-peptide contaminants.
What an analysis for MOTS-c should show
A useful certificate reports the column chemistry and dimensions, mobile phases and gradient, detection wavelength, retention time, the integrated main peak with its integration window visible, and a mass confirmation. For a peptide of this size, electrospray mass spectrometry typically shows several charge states rather than a single peak, and the deconvoluted mass should land at or near 2174.6 for the free peptide. Our article on mass spectrometry and peptide identity explains how to read those charge-state series.
Two sequence-specific features are worth looking for. The first is methionine oxidation: each methionine can gain an oxygen atom to form methionine sulfoxide, giving species at +16 Da and +32 Da that usually elute slightly earlier than the main peak. The second is tryptophan oxidation, which also adds mass in 16 Da steps. A certificate that shows small shoulders just ahead of the main peak and a mass spectrum with a +16 satellite is describing exactly these species, and a good report will say so rather than folding them into the main peak.
A good MOTS-c certificate separates net peptide content from chromatographic purity and identifies the counter-ion. With four basic side chains plus the free N-terminal amine, MOTS-c can carry several trifluoroacetate ions per molecule when supplied as a TFA salt, which adds measurable mass on top of the 2174.6 g/mol of the peptide itself. Our comparison of TFA vs acetate counter-ions covers why that matters for content, and peptide purity vs net peptide content explains why the two headline numbers are different.
Confirming identity independently
Search by sequence first, since MOTS-c is only a designation. Public chemical and protein databases index MOTS-c by structure and by sequence, and a search on MRWQEMGYIFYPRKLR will show quickly whether the formula and mass a vendor is quoting match the pairing used everywhere else. Its product page carries links that run the MOTS-c lookups for you.
How MOTS-c is supplied here
MOTS-c 10mg is supplied as a lyophilised powder in a sealed vial. Independent reverse-phase HPLC is run on MOTS-c, and the result sits on the product page. Vial size and HPLC purity for MOTS-c are both stated on its product page. A MOTS-c vial has no batch or lot marking; the crimp and cap color identify which published analysis it belongs to.
Frequently asked questions
What is the amino acid sequence of MOTS-c?
Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg (MRWQEMGYIFYPRKLR), sixteen standard L-amino acids.
What does the name MOTS-c stand for?
Mitochondrial open reading frame of the 12S rRNA-c. It names the location of the encoding sequence in the mitochondrial genome.
What molecular weight should I expect for MOTS-c?
Approximately 2174.6 g/mol for the free peptide, formula C101H152N28O22S2. Because a salt adds weight, the MOTS-c counter-ion needs to be stated next to the mass.
Why might a MOTS-c chromatogram show a small peak just before the main one?
The most common cause is oxidation of one of the two methionines (or the tryptophan), which makes the molecule slightly more polar and adds 16 Da. A mass spectrum of that peak will confirm it.
Research use only. All products supplied by Battle Born Peptides are laboratory reference materials for in-vitro research and analytical use by qualified professionals. They are not drugs, foods, dietary supplements, cosmetics or medical devices; they are not approved by the FDA or any other regulator for use in humans or animals; and they are not intended to diagnose, treat, cure, mitigate or prevent any disease, or to affect the structure or any function of the body of humans or animals. Nothing in this article is preparation, handling or dosing guidance. See our full research-use terms.