SS-31 (Elamipretide): Compound Reference for Researchers

A neutral reference sheet for SS-31, also known as elamipretide, a synthetic tetrapeptide studied for its interaction with a mitochondrial membrane lipid: structure, regulatory background and analytical notes.

At a glance

Property	Value
Names	SS-31, elamipretide; formerly MTP-131 and Bendavia; Szeto-Schiller peptide 31
Class	Synthetic tetrapeptide amide containing non-natural residues
Sequence	D-Arg-Dmt-Lys-Phe-NH2 (Dmt = 2′,6′-dimethyltyrosine)
Molecular formula	C32H49N9O5
Molecular weight	≈ 639.8 g/mol (average, free base); monoisotopic mass ≈ 639.39 Da
Form supplied	Lyophilized powder
Regulatory status	Elamipretide (as the hydrochloride, brand name Forzinity) received accelerated approval from the FDA on September 19, 2025 for a specific rare indication (Barth syndrome). Research-use material is not that product and is supplied for laboratory research only.

The formula calculated from the sequence matches the listed formula. Counter-ions (for example TFA, acetate or hydrochloride salts) add weight to the powder in the vial, so the mass of the salt form differs from the free-base values above. Compare any mass with the laboratory’s own result for the lot you hold.

What it is

SS-31 is a four-residue peptide whose sequence alternates a basic residue with an aromatic one. It contains two non-natural building blocks: a D-arginine and a dimethylated tyrosine (Dmt). Laboratory work describes it as interacting with cardiolipin, a lipid found in the inner mitochondrial membrane (references 1–4). It is made by chemical synthesis.

Regulatory and evidence context

Elamipretide has been through human clinical development, and in September 2025 the FDA granted accelerated approval to an elamipretide product for a specific, rare condition (reference 5). That approval concerns a regulated medicine manufactured and used under medical supervision. It does not apply to research-grade material, and nothing on this page is a statement about use outside the laboratory.

The larger research literature, much of it in cell and animal models, spans cardiac, renal, muscle, eye and other tissues (references 1–4). It is cited to show the breadth of the field, not to endorse any conclusion in it.

How to read the evidence

• Know which material a study used. Clinical findings describe a regulated medicine in a defined population. Laboratory findings describe the compound in experimental systems.
• Animal and cell results are not human results.
• Quality matters. Experimental work depends on the peptide being what the label says, adequately pure, and in a known salt form.

Analytical notes

These points follow from the structure (see our guides to reading a COA and to HPLC and mass spectrometry).

• Detection wavelength. The dimethyltyrosine and phenylalanine absorb in the ultraviolet, so the peptide is visible at 220 nm and near 280 nm. Always note the wavelength with a purity figure.
• Mass check. Positive-mode electrospray mass spectrometry would be expected to show [M+H]⁺ at about m/z 640.39 and a doubly charged ion near m/z 320.70.
• Stereochemistry. The D-arginine is part of the molecule, but ordinary mass spectrometry cannot tell D from L residues, so stereochemical analysis is needed to confirm it.
• Very short and charged. A tetrapeptide with two basic residues elutes early in reversed-phase HPLC, so the chromatogram deserves a careful look near the start of the run.
• Chemistry. There is no methionine, cysteine, asparagine or glutamine, so the common oxidation and deamidation pathways do not apply.

Handling and storage

General laboratory guidance for lyophilized peptides applies: store cold, dry, sealed and protected from light, let the vial reach room temperature before opening, and avoid repeated freeze–thaw cycles for any solution. Details are in our guide to research peptide storage and stability.

HLX Peptide documentation

• Product: SS-31 (elamipretide), 50 mg.
• Certificate: the certificate of analysis for lot SS31-1026-01 (tested Oct 4, 2026 by BT Labs; HPLC purity 99.9%) is published on the product page and on our certificates of analysis page.
• Our process: Quality & Testing
• Related references: BPC-157 · Thymosin Beta-4 · GHK-Cu · Tesamorelin · MOTS-c · NAD+
• Related guide: MOTS-c

References

1. Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Br J Pharmacol. 2014;171(8):2029–2050. PMID 24117165.
2. Birk AV, et al. The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. J Am Soc Nephrol. 2013;24(8):1250–1261. PMID 23813215.
3. Mitchell W, 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. PMID 32273339.
4. Mitchell W, et al. Structure-activity relationships of mitochondria-targeted tetrapeptide pharmacological compounds. eLife. 2022;11:e75531. PMID 35913044.
5. FDA accelerated approval of FORZINITY (elamipretide HCl), September 19, 2025, as reported in: IRCM news release; Mitoworld report. Check the FDA label for current details.

Last reviewed October 5, 2026. All products are sold strictly for laboratory research use only. Not for human or veterinary use, and not a drug, food, or cosmetic.