SS-31, also known as elamipretide, is a synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2,6-dimethyltyrosine.[6] It belongs to the Szeto-Schiller (SS) peptides, a class of...
SS-31, also known as elamipretide, is a synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2,6-dimethyltyrosine.[6] It belongs to the Szeto-Schiller (SS) peptides, a class of cell-permeable aromatic-cationic tetrapeptides that concentrate in the inner mitochondrial membrane.[1][3] Pepitiva supplies SS-31 as a lyophilized powder (10 mg vials, ≥98% purity) for in vitro and preclinical research.
SS-31 identity and specifications
Sequence: D-Arg-Dmt-Lys-Phe-NH2 (all residues L except D-arginine)[6]
Formula: C32H49N9O5 (free base)
Molecular weight: 639.8 g/mol (free base); salt forms weigh more[7]
Elamipretide is the active ingredient of a prescription medicine that the U.S. FDA granted accelerated approval in September 2025 to improve muscle strength in patients with Barth syndrome, a rare genetic disorder. Continued approval may depend on a confirmatory trial.[4][6] The research reagent sold here is not that medicine and is not intended for any clinical use.
For research use only. Not for human consumption.
Quality & Storage
≥98% purity. Lyophilized powder. Storage: -20°C. For research purposes only.
Mechanism of Action
Targeting the inner mitochondrial membrane
The SS peptides alternate aromatic and basic amino acids. In the first detailed report (2004), they entered cells and concentrated about 1000-fold in the inner mitochondrial membrane, reduced mitochondrial reactive oxygen species, inhibited the mitochondrial permeability transition and swelling, and prevented cytochrome c release. Analogs without dimethyltyrosine lost these effects.[1]
Cardiolipin and membrane electrostatics
Cardiolipin is a phospholipid of the inner mitochondrial membrane needed for cristae curvature, optimal activity of the respiratory complexes and assembly of supercomplexes. The inventor's group reports that SS-31 and related peptides selectively target cardiolipin, increase coupling efficiency and reduce reactive oxygen species production.[2] A 2020 biophysical study found that SS-31 binds the membrane interface in proportion to surface charge, alters lipid packing without destabilizing the bilayer, modulates the surface electrostatics of mitochondrial membranes and changes how mitochondria handle calcium stress.[3]
The inventor of the SS peptides founded the company that licensed the technology and disclosed a financial interest in it.[3]
Research Applications
Preclinical and clinical findings
Oxidative injury models (2004): SS peptides protected neuronal cells from oxidant-induced death at nanomolar concentrations and improved contractile force after ischemia-reperfusion in an isolated heart model.[1]
Aging models: a review by the inventor's group describes restoration of mitochondrial bioenergetics, cristae structure and organ function in aged animals.[2]
Primary mitochondrial myopathy (phase 3, 2023): in 218 adults, 24 weeks of elamipretide did not improve the 6-minute walk distance or fatigue scores compared with placebo; it was generally well tolerated.[5]
Barth syndrome: the basis of the 2025 U.S. accelerated approval, which relied on improvement in knee extensor muscle strength as an intermediate endpoint.[6]
This product is a research reagent sold for laboratory use only.
Storage & Handling Guidelines
Proper storage and handling are essential to maintain peptide integrity and ensure reliable research results. All Pepitiva Biolabs peptides are supplied as lyophilized (freeze-dried) powder, which provides excellent long-term stability when stored correctly. Store lyophilized peptides at -20°C for long-term storage or 2-8°C for short-term use. Once reconstituted, peptide solutions should be stored at 2-8°C and used within the timeframe specified in the product documentation. Always use sterile bacteriostatic water for reconstitution and handle peptides in a clean laboratory environment to prevent contamination. Avoid repeated freeze-thaw cycles, as thermal stress can cause peptide degradation and loss of biological activity.
Quality Control & Certification
This product is manufactured under strict quality control protocols and has been verified through comprehensive analytical testing. Each batch undergoes reverse-phase HPLC analysis for purity determination and electrospray ionization mass spectrometry (ESI-MS) for molecular identity confirmation. A detailed Certificate of Analysis (COA) is available for download, documenting purity percentage, molecular weight verification, appearance, and recommended storage conditions. Pepitiva Biolabs maintains batch-level traceability from synthesis through delivery, ensuring complete transparency and quality assurance for your research.
Frequently Asked Questions
What is SS-31?
SS-31 is a synthetic mitochondria-targeted tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2. Its nonproprietary drug name is elamipretide. "SS" stands for Szeto-Schiller, after the researchers who developed the peptide class.
Is SS-31 the same as elamipretide?
Yes. SS-31 is the laboratory code name and elamipretide is the international nonproprietary name of the same peptide.
Is elamipretide FDA approved?
Yes, for one indication. In September 2025 the FDA granted accelerated approval to an elamipretide medicine to improve muscle strength in patients with Barth syndrome; continued approval may depend on a confirmatory trial. The research reagent sold here is not that medicine.
How does SS-31 work?
It concentrates in the inner mitochondrial membrane, where it interacts with the phospholipid cardiolipin and changes the membrane's surface charge. In experimental models it reduced reactive oxygen species and inhibited the mitochondrial permeability transition.
What is the molecular weight of SS-31?
639.8 g/mol for the free base (C32H49N9O5, PubChem). Salt forms are heavier; for example, the trihydrochloride described in the FDA label is 749.2 g/mol.
How should SS-31 be stored?
Keep the lyophilized powder at −20 °C, protected from light and moisture.
Is this product approved for human use?
No. This product is intended exclusively for in vitro scientific research and laboratory use. It is not approved for human or veterinary use, not intended for diagnostic or therapeutic purposes, and should not be administered to humans or animals under any circumstances.
How do I reconstitute this peptide?
Add sterile bacteriostatic water slowly to the vial, directing the stream against the glass wall rather than directly onto the lyophilized powder. Gently swirl the vial until the powder is fully dissolved — do not shake vigorously. The recommended reconstitution volume depends on your desired concentration. Refer to the product documentation for specific guidance.
Can I get a Certificate of Analysis (COA)?
Yes. A Certificate of Analysis is included with every order and is also available for download from the product page. The COA documents HPLC purity, mass spectrometry identity confirmation, batch number, production date, and storage recommendations.
Scientific References
Zhao K, Zhao GM, Wu D, et al. Cell-permeable peptide antioxidants targeted to inner mitochondrial membrane inhibit mitochondrial swelling, oxidative cell death, and reperfusion injury. J Biol Chem. 2004;279(33):34682-34690. PubMed
Szeto HH, Liu S. Cardiolipin-targeted peptides rejuvenate mitochondrial function, remodel mitochondria, and promote tissue regeneration during aging. Arch Biochem Biophys. 2018;660:137-148. PubMed
Mitchell W, Ng EA, Tamucci JD, et al. The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action. J Biol Chem. 2020;295(21):7452-7469. PubMed
Shirley M. Elamipretide: First Approval. Drugs. 2026;86(3):377-383. PubMed
Karaa A, Bertini E, Carelli V, et al. Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology. 2023;101(3):e238-e252. PubMed
U.S. FDA, Drugs@FDA. NDA 215244 (elamipretide hydrochloride), original approval 09/19/2025, accelerated approval; prescribing information. Source
PubChem. Elamipretide, CID 11764719: C32H49N9O5, 639.8 g/mol, CAS 736992-21-5. Source
Sources are peer-reviewed publications indexed in PubMed and trial registrations on ClinicalTrials.gov. Each citation was checked against its PubMed record.
For research use only. Not for human consumption.
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