What is MOTS-c?
MOTS-c stands apart from the nuclear-encoded peptides in this catalog because its open reading frame sits inside mitochondrial DNA. Our molecular records give CAS 1627580-64-6, formula C101H152N28O22S2, an average molecular weight of 2174.6, and the full 16-residue sequence H-Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg-OH.
That sequence explains most of its handling behaviour. Two methionines account for the two sulfur atoms in the formula and make oxidation the primary degradation route to design against. Three arginines and a lysine give a strongly basic net charge and good aqueous solubility, while the tryptophan and two tyrosines make the peptide light-sensitive and give it usable absorbance near 280 nm.
In the published literature MOTS-c is studied as a regulator of metabolic homeostasis. Cell work links it to AMP-activated protein kinase activation and to the folate and methionine one-carbon pathway, and rodent studies have used it to model age-associated changes in insulin sensitivity and exercise capacity. No receptor has been agreed on, the route by which an exogenous peptide reaches the cytosol and nucleus is unresolved, and the significance of circulating concentrations is debated.
Reconstitution & handling
Sterile or bacteriostatic water dissolves the lyophilized cake readily given the basic residue content. Add the diluent slowly against the vial wall and swirl rather than vortex. Because the two methionines are oxidation-prone, prepare solutions with freshly drawn water and keep contact with headspace air brief. Concentration follows from labelled mass divided by diluent volume, corrected by net peptide content where molarity must be exact.
Storage & stability
Store the sealed dry vial at -20 °C with desiccant and away from light. Reconstituted material belongs at 2 to 8 °C in single-use aliquots and should not be cycled through the freezer, since methionine oxidation and tryptophan photodegradation both accelerate in dilute solution. Amber vials or foil are worth using here rather than optional, given the tryptophan and tyrosine content.
How it's tested
Lots are released on reversed-phase HPLC purity at 214 and 220 nm, where methionine sulfoxide species resolve ahead of the main peak when present. Identity is confirmed by mass spectrometry against the theoretical average mass of 2174.6. Net peptide content, water content and residual acetate are reported alongside purity, and the lot-matched certificate of analysis with chromatogram and spectrum accompanies the specific vial on request.