What SS-31 is
SS-31 is a synthetic tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2,6-dimethyltyrosine. It belongs to the Szeto-Schiller (SS) peptides designed by Hazel Szeto and Peter Schiller and first described in the early 2000s. The SS peptides share an alternating aromatic-cationic pattern that lets them cross cell membranes and concentrate in mitochondria. SS-31 has also been developed under the names elamipretide, MTP-131 and Bendavia.
Mechanism and research models
SS-31 associates with the inner mitochondrial membrane, where it interacts with cardiolipin, a phospholipid that helps hold the respiratory-chain complexes together. Structure-activity work suggests much of its effect comes from changing the electrostatics of the membrane surface (Mitchell et al., 2022).
Preclinical studies use it as a mitochondria-targeted tool in models of aging muscle and mitochondria (Pharaoh et al., 2023), lipopolysaccharide-induced neuroinflammation in mice (Zhao et al., 2019), and a range of cardiac, renal and neurodegenerative models summarized by Tung et al. (2025).
Regulatory status (October 2026)
Elamipretide is the first compound in this class to reach approval. On September 19, 2025, the FDA granted accelerated approval to Forzinity (elamipretide), from Stealth BioTherapeutics, for Barth syndrome in patients weighing at least 30 kg. The approval rests on improved knee-extensor muscle strength, and a confirmatory trial is required. Research-grade SS-31 is a laboratory reference material, not Forzinity, and is not for human use.
SS-31 vs. MOTS-c
Both are studied in mitochondrial research but work very differently. SS-31 is a designed synthetic peptide that targets the mitochondrial membrane from outside the cell. MOTS-c is a naturally occurring peptide encoded in mitochondrial DNA itself, studied mainly as a metabolic signalling molecule. See also NAD+.
Common questions
Is SS-31 the same as elamipretide?
Yes, elamipretide is the nonproprietary name for SS-31. The FDA-approved drug product is Forzinity; research-grade SS-31 is a separate laboratory material.
When was elamipretide approved?
The FDA granted accelerated approval to Forzinity for Barth syndrome on September 19, 2025.
How does SS-31 reach mitochondria?
Its alternating aromatic and positively charged residues let it cross cell membranes and accumulate at the inner mitochondrial membrane, where it interacts with cardiolipin.
Background sources
- FDA grants accelerated approval to first treatment for Barth syndrome (FDA, September 2025)
- Structure-activity relationships of mitochondria-targeted tetrapeptide pharmacological compounds (eLife, 2022)
- Elamipretide: a review of its structure, mechanism of action, and therapeutic potential (Int J Mol Sci, 2025)
Chemistry & identity
| CAS Number | 736992-21-5 |
|---|---|
| Molecular Formula | C32H49N9O5 |
| Molecular Weight | 639.8 g/mol |
| Residue Count | 4 |
| PubChem CID | 11764719 |
Peptide sequence
RXKF
Research context
PubChem synonym: Arg-Dmt-Lys-Phe-NH2; X = 2,6-dimethyltyrosine (Dmt) at position 2.
Selected research references
Published peer-reviewed literature on SS-31 (Elamipretide). Provided for research-context purposes only; Central Coast Peptides does not make claims about outcomes in humans.
- Elamipretide (SS-31) improves mitochondrial dysfunction, synaptic and memory impairment induced by lipopolysaccharide in mice
- Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential
- The mitochondrially targeted peptide elamipretide (SS-31) improves ADP sensitivity in aged mitochondria by increasing uptake through the adenine nucleotide translocator (ANT)
Related lab guides
- How to read a peptide certificate of analysis (COA) · HPLC purity, mass spec identity and net peptide content
- How to store lyophilized peptides · Temperature, moisture and light
- Reconstitution calculator · Concentration and mg per 0.1 mL for any vial size
SS-31 (Elamipretide) for laboratory research
Central Coast Peptides supplies SS-31 (Elamipretide) as a lyophilized reference material with a third-party COA. Ships from California.
View SS-31 (Elamipretide) kits, single vials, and boxes →