MOTS-C: A Mitochondrial-Derived Peptide Research Reference

MOTS-C: A Mitochondrial-Derived Peptide Research Reference

MOTS-C occupies an unusual position among research peptides. Most synthetic peptides in laboratory supply correspond to sequences encoded in nuclear DNA, or are entirely artificial constructs. MOTS-C belongs to a small class encoded within the mitochondrial genome — a genuinely distinct area of molecular biology, and the reason the compound attracts research interest as a structural subject.

This reference covers origin, sequence, molecular identity and analytical characterisation. No use of any kind is described.

Mitochondrial origin

Mitochondria carry their own small circular genome, separate from the chromosomal DNA in the cell nucleus. Human mitochondrial DNA is approximately 16,600 base pairs and encodes a limited set of gene products, most associated with the respiratory chain.

MOTS-C — the name derives from Mitochondrial Open reading frame of the Twelve S rRNA type-C — is encoded within the 12S ribosomal RNA region of that mitochondrial genome. This makes it a member of the mitochondrial-derived peptide class, a group identified relatively recently in the history of molecular biology and still an active area of structural investigation.

For a research supplier this origin is a point of chemical interest rather than a functional claim. The peptide supplied in a vial is a synthetic construct reproducing a naturally occurring sequence, made by the same solid-phase methods used for any other peptide.

Chemical identity and sequence

MOTS-C carries CAS registry number 1627580-64-6. Its molecular formula is C101H152N28O22, giving a molecular weight of approximately 2,174.6 g/mol. The peptide comprises sixteen amino acid residues with the sequence MRWQEMGYIFYPRKLR in standard single-letter notation.

Reading that sequence tells an analyst several useful things before any instrument is involved. It contains two methionine residues (M) and a tryptophan (W) — all three are among the residues most susceptible to oxidation. It contains a tyrosine pair (Y) and a phenylalanine (F), aromatic residues that dominate ultraviolet absorbance at 280 nm. And it carries three arginine residues and a lysine, giving the molecule a strongly basic character that influences both chromatographic retention and ionisation behaviour in mass spectrometry.

Oxidation and the impurity profile

The methionine and tryptophan content is analytically significant. Methionine oxidises readily to the sulfoxide, adding 16 g/mol per oxidised residue — a mass shift small enough to require reasonable instrument resolution but entirely detectable by LC-MS. Tryptophan oxidation produces a more complex set of products.

A well-characterised MOTS-C batch will therefore often show minor oxidation-related species in its chromatographic profile, and understanding that these are expected rather than anomalous is part of reading the analytical data correctly. Their proportion, not their presence, is the meaningful figure.

Analytical verification

Research-grade MOTS-C is typically specified at greater than 98% purity by HPLC with identity confirmed by LC-MS. At 2,174.6 g/mol the peptide sits in a mass range where multiple charge states are commonly observed and deconvolution is routine.

The strongly basic residue content generally makes the molecule ionise efficiently in positive-mode electrospray, which is helpful for identity confirmation. The same basicity affects reversed-phase retention, and method conditions are usually adjusted accordingly.

Physical form

MOTS-C is supplied as a lyophilised powder, white to off-white, in a sealed glass research vial. Given the oxidation-susceptible residues in the sequence, the sealed dry state is particularly relevant for this compound: oxygen exposure and moisture are the two environmental variables most likely to shift the impurity profile over time.

Synthesis considerations

At sixteen residues MOTS-C sits in a middle range for solid-phase synthesis: long enough that deletion sequences are a genuine concern, short enough that a well-run synthesis should reach high purity without extraordinary measures. Fifteen coupling steps are required to assemble the chain.

The sequence contains features that complicate matters. Consecutive hydrophobic residues can promote aggregation of the growing chain on the resin, which reduces coupling efficiency at those positions. The arginine residues require side-chain protection that must be removed cleanly at the end without damaging the tryptophan, which is itself sensitive to the acidic conditions used for deprotection.

These are routine problems with established solutions, but they shape the impurity profile. A MOTS-C batch is more likely to show deletion sequences at specific positions than randomly distributed ones, which is why chromatographic characterisation is more informative than a single purity number.

Documentation and batch specificity

Analytical documentation for MOTS-C should state the batch identifier, the methods applied, the purity obtained and the observed mass. Given the oxidation-susceptible residues, a thorough specification may also report on oxidation-related species specifically rather than folding them into a general impurity total.

Because every synthesis run differs, these figures describe one batch and cannot be transferred to another. Documentation without a batch reference, or that cannot be matched to a marking on the vial, is substantially weaker evidence than it appears.

Storage-relevant chemistry

The two methionines and the tryptophan make oxygen exposure the environmental variable of most consequence for this compound. Oxidation is not reversed by subsequent good storage; once a methionine has become the sulfoxide it remains so.

In the sealed, lyophilised state, oxygen availability is limited and molecular mobility is low, so the reaction proceeds slowly. The integrity of the vial seal is therefore doing real chemical work rather than merely keeping contamination out.

Corix Labs supplies MOTS-C 10mg and MOTS-C 40mg as lyophilised research preparations, each verified by HPLC and LC-MS at batch level.

Corix Labs publishes analytical documentation for its research materials. See third-party testing reports for further detail on how batches are verified.

All materials referenced in this article are supplied strictly for laboratory research and analytical use. They are not licensed medicines and are not sold for use in humans or animals. Nothing in this article constitutes guidance on administration, preparation for use, or any clinical, therapeutic, diagnostic or cosmetic application.