SS-31 (Elamipretide) Research Guide 2026: Cardiolipin Chemistry, COA & Handling

SS-31 (elamipretide) is a synthetic mitochondria-targeted tetrapeptide and one of the most-studied tools in mitochondrial membrane research. This SS-31 research guide covers what a laboratory purchaser actually needs: sequence, CAS number, molecular weight, the cardiolipin-binding mechanism described in the literature, how the research compound differs from the 2025 FDA-approved drug product, and how to verify purity on a certificate of analysis. For Research Use Only. Not for human consumption.

What Is SS-31 (Elamipretide)?

SS-31 belongs to the Szeto-Schiller family of cell-permeable peptides, named for researchers Hazel Szeto and Peter Schiller, whose work described small aromatic-cationic peptides that concentrate in the inner mitochondrial membrane. The same molecule has circulated under several designations — SS-31, MTP-131, Bendavia and, in its pharmaceutical development, elamipretide. When comparing supplier listings, papers and database entries, treat these as one compound.

It is short: four residues with an amidated C-terminus. Two of those residues are non-standard, which matters for both synthesis and analytical verification.

SS-31 Sequence, CAS Number and Molecular Weight

The reference identifiers below are the values published in public chemical databases such as PubChem. Use them to cross-check any certificate of analysis rather than relying on listing copy alone.

Sequence: D-Arg-Dmt-Lys-Phe-NH2 (Dmt = 2',6'-dimethyltyrosine)

CAS number (free base): 736992-21-5

Molecular formula: C32H49N9O5

Molecular weight: approximately 639.8 g/mol (free base)

Note the salt form. Research material is often supplied as an acetate or hydrochloride salt, and a salt changes the observed mass per vial versus the free-base figure. A COA should state which form you are holding.

The Cardiolipin Mechanism Described in the Literature

Most published interest in SS-31 centers on cardiolipin, a phospholipid found almost exclusively in the inner mitochondrial membrane, where it helps organize the electron transport chain. Preclinical studies describe SS-31 as binding reversibly to cardiolipin, and much of the research literature uses it as a probe for cardiolipin interactions, membrane organization and mitochondrial bioenergetics in cell and animal models.

That places SS-31 alongside other mitochondrially oriented research compounds. Investigators frequently read it next to MOTS-c, a mitochondrial-derived peptide, and SLU-PP-332, a nuclear-receptor agonist. The mechanisms are unrelated — a cardiolipin binder is neither a mitochondrial-derived peptide nor a receptor agonist — but the research questions overlap.

Research Compound vs. the FDA-Approved Drug

In September 2025 the FDA granted accelerated approval to FORZINITY (elamipretide HCl), developed by Stealth BioTherapeutics, for a specific indication in Barth syndrome, an ultra-rare mitochondrial disease. That is a finished, regulated pharmaceutical product manufactured and labeled under FDA oversight.

Research-grade SS-31 is not that product. It is a laboratory reagent sold for in-vitro and preclinical work, carries no approved indication, and must not be substituted for, compared to, or represented as a prescription medicine. The approval is a milestone for the molecule's scientific history; it does not change the regulatory status of research material.

Handling, Reconstitution and Storage

SS-31 is typically supplied as a lyophilized powder. General peptide handling practice applies: keep unopened vials cold, dry and protected from light; let a vial reach room temperature before opening to limit condensation; and record the lot number against every experiment. For solvent selection and technique, work from your lot's technical data and our peptide reconstitution guide. For short- and long-term storage conditions, see the peptide storage and handling guide.

How to Verify SS-31 Purity on a COA

Because two residues are non-standard and the first is a D-amino acid, a credible SS-31 certificate should show more than a single purity number:

HPLC purity with the chromatogram, not just a percentage.

Mass spectrometry showing an observed mass consistent with the ~639.8 g/mol free base (adjusted for the stated salt form).

A lot number that matches the label on your vial.

Our walkthrough on how to read a peptide COA explains each field, and our lab testing page covers how Precision Labs documents third-party testing. Precision Labs supplies SS-31 (elamipretide) 50mg for qualified research use.

SS-31 (Elamipretide) FAQ

Is SS-31 the same compound as elamipretide?

Yes. SS-31, MTP-131, Bendavia and elamipretide are designations for the same tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2.

What is the CAS number for SS-31?

The free base is listed under CAS 736992-21-5, with a molecular formula of C32H49N9O5 and a molecular weight of about 639.8 g/mol.

Is research-grade SS-31 the same as FORZINITY?

No. FORZINITY is an FDA-approved drug product with a specific labeled indication. Research-grade SS-31 is a laboratory reagent with no approved use and is not a substitute for any medicine.

What should an SS-31 certificate of analysis include?

An HPLC chromatogram, a mass spectrometry result consistent with the expected mass for the stated salt form, and a lot number that matches your vial.

Can SS-31 be used in humans?

No. Research-grade SS-31 is sold strictly for laboratory research. It is not for human or veterinary use, and no dosing information is provided.

Source SS-31 With Documentation You Can Check

If your lab needs SS-31 with lot-matched HPLC and mass spec documentation, contact Precision Labs for current COAs and availability.

For Research Use Only. Not for human consumption. Precision Labs products are intended solely for in-vitro and laboratory research by qualified professionals. No statements on this page have been evaluated by the FDA, and nothing here is intended to diagnose, treat, cure or prevent any disease.