×10 · 10-vial kit

SS-31

Also known as elamipretide. Lyophilized, vacuum-sealed, 10-vial kit.

CAS: 736992-21-5
Form: Lyophilized powder
Storage: Frozen, in the dark
Ships: Kits by Dec 12, 2026

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SS-31 is a synthetic tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2, whose nonproprietary name is elamipretide. It was designed by Hazel Szeto and Peter Schiller as a cell-permeable peptide that concentrates in the inner mitochondrial membrane, where it binds the phospholipid cardiolipin. In September 2025 the FDA granted accelerated approval to elamipretide under the brand name Forzinity.

Supplied for laboratory research use only. Not for human or veterinary use, and not for diagnostic or therapeutic application.

SS-31: compound data

Molecular formula: C₃₂H₄₉N₉O₅
Molecular weight: 639.8 g/mol
CAS number: 736992-21-5
PubChem: CID 11764719
Form supplied: Lyophilized powder, vacuum-sealed
Concentration: mg/mL and molarity calculator

Reference values from PubChem, the chemistry database of the US National Library of Medicine, for the compound as registered there.

About SS-31

Structure of SS-31

SS-31 has four residues: D-arginine, 2,6-dimethyl-L-tyrosine (Dmt), L-lysine and L-phenylalanine, with the C-terminus as an amide. Two features are unusual for so short a peptide: the first residue is the D-form of arginine, and Dmt is a tyrosine carrying two methyl groups on its ring. Basic and aromatic residues alternate along the chain, and a 2013 study gives the net charge as 3+ at physiologic pH. The FDA label for the approved product describes the drug substance as a hydrochloride salt with three HCl per peptide; research material may be a different salt, which changes the formula weight.

Where SS-31 comes from

The SS in the name stands for Szeto and Schiller. The founding paper, by Zhao and colleagues at Weill Medical College of Cornell University in the Journal of Biological Chemistry in 2004, describes a set of peptide antioxidants built on alternating aromatic and basic residues, with dimethyltyrosine providing the scavenging property. It reports that these peptides enter cells and concentrate about 1000-fold in the inner mitochondrial membrane. The compound later took the code MTP-131 and the name Bendavia during commercial development, and elamipretide is its USAN and INN. PubChem also lists RX-31 and Ocuvia.

What SS-31 binds

SS-31 has no protein receptor. Its described target is cardiolipin, a phospholipid of the inner mitochondrial membrane. Birk and colleagues in 2013 built a fluorescent analog containing the polarity-sensitive amino acid aladan and showed selective binding to cardiolipin with a dissociation constant near 1.9 micromolar, through both electrostatic and hydrophobic contacts. They also reported that the peptide inhibited the peroxidase activity that cytochrome c acquires when bound to cardiolipin, by protecting the bond between methionine 80 and the heme iron. The FDA label calls elamipretide a mitochondrial cardiolipin binder that localizes to the inner mitochondrial membrane.

SS-31 in the research literature

The 2004 paper used neuronal N2A cells exposed to t-butylhydroperoxide, isolated mitochondria challenged with calcium or 3-nitropropionic acid, and an ex vivo heart model, and measured reactive oxygen species, permeability transition, swelling and cytochrome c release. Analogs lacking dimethyltyrosine served as controls. The 2013 study added binding experiments with a fluorescent analog and a rat model of renal ischemia. In people, elamipretide was studied by Stealth BioTherapeutics in the human trials that supported the 2025 approval, and ClinicalTrials.gov lists a further study, 4TAZPower (NCT07531251), as Phase 4 and recruiting.

Regulatory status of SS-31

Elamipretide is an approved drug in the United States, for a single labeled indication that the FDA label sets out. On September 19, 2025 the FDA approved Forzinity (elamipretide) injection under NDA 215244, held by Stealth BioTherapeutics. It is an accelerated approval under section 506(c) and 21 CFR 314.510, so continued approval depends on a confirmatory study, and the approval letter is the primary record of its terms. Research-grade SS-31 is not that product. Anhydrolabs supplies it as a reference reagent for in-vitro laboratory research only, not for human or veterinary diagnosis, treatment, or consumption.

Handling SS-31 in the laboratory

The material is a lyophilized powder in a vacuum-sealed vial. Keep it frozen at -4 °F and protected from light. Let the vial reach room temperature before breaking the seal, so that moisture from the air does not condense on the cold powder. Once dissolved for in-vitro work, a solution keeps for about four weeks at 39 °F. Divide a stock solution into single-use aliquots instead of freezing and thawing it repeatedly. The FDA label describes elamipretide hydrochloride as freely soluble in water, which fits a small peptide with three basic groups. Check which salt a lot is before converting weighed mass to molar concentration.

Sources

Research notes on SS-31

SS-31 (Elamipretide): A Mitochondria-Targeted PeptideThe SS-31 peptide (elamipretide): its D-Arg-Dmt-Lys-Phe-NH2 sequence, how it binds cardiolipin, its Szeto-Schiller origin and its 2025 FDA status.

Sizes and kits

Volume pricing is quoted on request; see wholesale.

2 sizes · 2 kits

Size	Pack	SKU	Availability	Price
10 mg	Single vial	AL-SS-31	Coming soon	$44.95
10 mg	10-vial kit	AL-SS-31-K10	Presale	$202.50~~$225.00~~$20.25/vial
50 mg	10-vial kit	AL-SS-31-50MG-K10	Presale	$630.00~~$700.00~~$63.00/vial

Storage and reconstitution

Vials are sealed under vacuum. Store lyophilized material frozen at −4 °F, protected from light. Full detail is on the storage and handling page.

Research-use statement

Supplied as a reference reagent for laboratory research use. Not for human or veterinary use, and not for diagnostic or therapeutic application. Read the full research-use statement.

SS-31: common questions

Is elamipretide the same as SS-31?

Yes. elamipretide is another name for SS-31 (CAS 736992-21-5). It is the same compound, supplied here as a lyophilized powder for in-vitro laboratory research use only.

What is SS-31 supplied as?

SS-31 is supplied as a lyophilized (freeze-dried) powder in a vacuum-sealed vial, in 10 mg and 50 mg, for in-vitro laboratory research use only.

Is SS-31 available as a 10-vial kit?

Yes. SS-31 comes in a 10-vial kit: 10 mg for $202.50 ($20.25 per vial); 50 mg for $630.00 ($63.00 per vial), presale prices. A kit is ten sealed vials of the same size, priced below ten single vials.

When do SS-31 presale kits ship?

By Dec 12, 2026. Presale kits are 10% off. If we cannot ship by Dec 12, 2026, we tell you before that date and you can cancel for a full refund.

What is the CAS number of SS-31?

The CAS registry number of SS-31 is 736992-21-5.

How should SS-31 be stored?

Frozen at −4 °F and protected from light, from the day it arrives. Let the vial reach room temperature before breaking the seal; once reconstituted, stability holds for about four weeks refrigerated at 39 °F.

How fast does SS-31 ship?

Presale kits ship from the United States by Dec 12, 2026, to US addresses. Sizes marked in stock ship within 1 business day of payment.

Is SS-31 for human use?

No. It is supplied as a reference reagent for laboratory research use. Not for human or veterinary use, and not for diagnostic or therapeutic application.

What is the sequence of SS-31?

SS-31 is D-Arg-Dmt-Lys-Phe-NH2. Dmt is 2,6-dimethyl-L-tyrosine, and the C-terminus is an amide. The first residue is D-arginine, the mirror-image form of the natural amino acid, and the peptide carries a net charge of 3+ at physiologic pH.

What does SS-31 bind?

SS-31 binds cardiolipin, a phospholipid of the inner mitochondrial membrane, and no protein receptor has been described for it. A 2013 study using a fluorescent analog measured a dissociation constant of about 1.9 micromolar and found that the bound peptide inhibited the peroxidase activity of the cytochrome c and cardiolipin complex.

Is SS-31 approved by the FDA?

Under the name elamipretide, yes. The FDA granted accelerated approval to Forzinity on September 19, 2025, under NDA 215244, for a single labeled indication. Research-grade SS-31 is a laboratory reagent and is not that finished product.

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