MOTS-c USA

MOTS-c has an unusual pedigree: it is encoded in the mitochondrial genome rather than the nuclear one, inside the 12S ribosomal RNA gene. The synthetic peptide we supply is the same sixteen-residue sequence made by solid-phase synthesis, and it happens to be one of the more analytically demanding compounds in the catalogue. This page covers why, how it differs from SS-31, and how to order within the United States.

Sequence and what it implies

MOTS-c is Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg, calculated monoisotopic mass close to 2,174 Da. Two methionines give it two oxidation sites. A tryptophan and two tyrosines give it strong 280 nm absorbance and a light sensitivity to manage. Three arginines and a lysine make it basic, so the counter-ion contribution to vial mass is real. MOTS-c explained covers the origin of the sequence, and MOTS-c and SS-31 in mitochondrial research places it in the literature.

MOTS-c is not SS-31

The two are grouped together in catalogues because both are studied in mitochondrial contexts. Structurally they have nothing in common. SS-31 (elamipretide) is a four-residue synthetic peptide, D-Arg-Dmt-Lys-Phe-NH2, mass near 640 Da, with a non-standard dimethyltyrosine and no mitochondrial-genome origin at all. We stock SS-31 10 mg separately; SS-31 and cardiolipin targeting covers the molecule on its own terms.

The two-wavelength check

Because MOTS-c absorbs at 280 nm as well as 220 nm, a certificate can report purity at both, and the two figures should be read together. Impurities without aromatic residues are invisible at 280 nm, so the 280 nm purity will usually be the higher of the two and the 220 nm figure the conservative one. Where a laboratory reports only 280 nm, ask for the 220 nm trace. UV response factors and purity comparison explains why the same vial can give two different honest numbers, and diode-array peak purity covers how a spectrum across the main peak adds a third check.

Oxidation on the certificate

Each methionine that oxidises to the sulfoxide adds 16 Da and shifts the peak earlier on a reversed-phase column. A fresh batch shows a main peak at about 2,174 Da with little or nothing at 2,190 and 2,206. A certificate with a substantial +16 shoulder is describing material that has already begun to age. The methionine chemistry is the same one described for Semax in methionine oxidation, and forced degradation studies explain how a laboratory confirms its method can see the oxidised forms at all.

Handling in solution

Lyophilised MOTS-c is stable at minus 20 °C in a sealed vial. Reconstituted, it is among the less forgiving peptides we stock: methionine oxidises in the presence of dissolved oxygen, tryptophan degrades under light, and the hydrophobic residues drive adsorption to plastics at low concentration. Reconstitute in degassed water or buffer, aliquot at once, keep aliquots frozen and dark, and use low-bind tubes for dilute working solutions. Light, oxygen and temperature covers the mechanisms.

Sizes and ordering in the USA

We supply MOTS-c 10 mg and MOTS-c 20 mg, both lyophilised at 99%+ purity, with the larger vial cheaper per milligram. Orders ship domestically within the United States with no import processing; USPS, UPS and FedEx are offered at checkout, dispatch is within one business day and typical transit is two to five days. Published certificates are on the certificates page, and the price list shows both sizes alongside SS-31 and NAD+ for a mitochondrial panel.

Research use only

MOTS-c from ExoLabz is a laboratory reference material for in vitro and analytical research. It is not a drug and not for human or veterinary use, and we do not provide dosing or administration information. The purity guarantee applies to every vial.