# MOTS-c Peptide Testing: What to Verify Before You Use It
MOTS-c is a 16-residue peptide encoded within the mitochondrial 12S rRNA. It is studied for its role in metabolic signaling, insulin sensitization, and cellular stress response. Because it is short, unmodified, and readily synthesized, MOTS-c is easier to make than the GLP-1 class lipopeptides — but that also means the market has a wide quality range.
What MOTS-c actually is
- Sequence: MRWQEMGYIFYPRKLR (16 residues)
- Theoretical monoisotopic mass: approximately 2174.09 Da
- No lipid modification, no PEGylation, no disulfide
- Solubility: soluble in aqueous buffer at neutral pH
Purity by HPLC
MOTS-c is straightforward on a standard C18 method. Competent synthesis routinely delivers ≥98% by HPLC area at 214 nm. Below 95% suggests old material or poor SPPS cleanup.
Impurity peaks to watch for:
- Met1 oxidation — N-terminal Met can oxidize during synthesis and long storage.
- Trp3 oxidation — Trp is oxidation-prone. Shows as a shoulder on the main peak.
- Deletion sequences — single-residue omissions.
Identity by LC-MS
Positive mode ESI. Expect singly and doubly charged states. Deconvoluted mass should land within a few ppm of 2174.09 Da. Because MOTS-c is short, mass measurement is particularly sensitive to deletion sequences — des-Met (loss of 131 Da) or des-Trp (loss of 186 Da) shows up clearly.
