SS-31 50mg

What is SS-31 ?

SS-31, also written SS31, is a synthetic mitochondria-targeted tetrapeptide. In the clinical literature it is elamipretide, and earlier development names were MTP-131 and Bendavia. SS-31 is sold here as white lyophilised powder in 10mg and 50mg vials.

The sequence is D-Arg-Dmt-Lys-Phe-NH₂, where Dmt is 2′,6′-dimethyltyrosine. Alternating cationic and aromatic residues give it a net positive charge while letting it cross membranes. The D-arginine and the unnatural Dmt residue make the backbone resistant to proteolysis.

Its target is a lipid, not a receptor. SS-31 binds cardiolipin, the phospholipid of the inner mitochondrial membrane that cristae need to form (Birk et al., J Am Soc Nephrol, 2013).

SS-31 Research Applications

• Bioenergetics models : isolated mitochondria and permeabilised-fibre respirometry, membrane potential and ATP recovery assays, and reactive oxygen species measurement.
• Ischaemia-reperfusion : renal and cardiac models built on the cristae-protection findings of Birk and colleagues.
• Cardiolipin chemistry : peptide binding and cytochrome c peroxidase studies in model membranes.
• Clinical literature : a Phase I/II trial in primary mitochondrial myopathy (Karaa et al., Neurology, 2018), then a Phase 3 trial that missed its primary endpoints (Karaa et al., Neurology, 2023).

In 2025 the US FDA granted elamipretide accelerated approval for Barth syndrome, under the name Forzinity (Bedoyan and Vockley, Cell Metab, 2026). The research-grade SS-31 sold here is not that medicine. It is supplied for in-vitro laboratory research only.

Why Cardiolipin Targeting Is Studied

Most peptides act through a receptor expressed on particular cell types. Cardiolipin sits in the inner membrane of every mitochondrion, so one tool compound can be used in cardiac, renal, skeletal muscle or neuronal preparations. Birk and colleagues showed the SS-31 and cardiolipin complex blocks the peroxidase activity of cytochrome c, which otherwise oxidises cardiolipin during ischaemia. In rat kidney ischaemia, pretreatment protected cristae, prevented mitochondrial swelling and sped ATP recovery on reperfusion. The same ubiquity is a caution: tissue selectivity cannot be assumed, so attribute effects by measurement.

Research Overview

SS-31, also written SS31 and known in the clinical literature as elamipretide, MTP-131 or Bendavia, is a synthetic aromatic-cationic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH₂, where Dmt is 2,6-dimethyltyrosine, a non-proteinogenic tyrosine analogue carrying methyl groups on the two ring positions flanking the phenolic hydroxyl. Its molecular formula is C₃₂H₄₉N₉O₅, molecular weight 639.79 g/mol, CAS number 736992-21-5. The alternating cationic and aromatic residues give the molecule a net positive charge at physiological pH while leaving it membrane-permeant, and the D-configured arginine together with the unnatural Dmt residue confers resistance to proteolytic degradation. Mechanistically, SS-31 is unusual in this catalogue because its target is not a receptor at all. Birk and colleagues (J Am Soc Nephrol, 2013) demonstrated that the peptide concentrates in the inner mitochondrial membrane by interacting with cardiolipin, the signature phospholipid of that membrane, and that in ischaemia models this interaction re-energised the mitochondria, improving electron transport chain function and reducing reactive oxygen species generation. Because cardiolipin is present in essentially every mitochondrion rather than in one tissue type, the compound is studied across cardiac, renal, skeletal muscle and neuronal bioenergetics models. SS-31 also has something almost no other compound in this catalogue has: genuine randomised controlled trial history. Karaa and colleagues (Neurology, 2018) published a randomised dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy. The honest completion of that story is that later Phase 3 work was mixed, the SPIMM-301 trial in the same indication did not produce unambiguously positive outcomes, so elamipretide remains an investigational compound with no marketing authorisation in the UK or anywhere else. The trial record distinguishes the molecule; it does not license it. Each vial contains 50mg of SS-31 as white lyophilised powder, batch UKPL-753, recorded at 99.1% purity by RP-HPLC, certificate published on this page. Supplied strictly for in-vitro laboratory research use only.

Storage and Reconstitution

Keep sealed vials at -20°C, away from light and moisture. After reconstitution, keep the solution at 2-8°C and use it within 4 weeks, or freeze single-use aliquots at -20°C. Oxidation of the phenolic Dmt ring is the degradation route to guard against, so store solutions dark with little headspace and avoid repeated freeze-thaw cycles.

Vials are sold on their own, without bacteriostatic water for mixing or other supplies.

How to reconstitute and handle

Bring the vial to room temperature and swab both stoppers with alcohol. Add bacteriostatic water slowly down the inside wall of the vial. SS-31 is highly water-soluble and a clear, colourless solution forms almost at once, so there is no need to shake. The Dmt ring is phenolic, so keep the solution away from strong oxidisers and bright light. Label the vial with the reconstitution date.

• A 639.79 g/mol tetrapeptide dissolves rapidly and needs no agitation, never shake or vortex.
• Aliquot reconstituted stock into single-use volumes and avoid repeated freeze-thaw cycles. Label each aliquot with the reconstitution date for experimental reproducibility.

For the full method, see the peptide reconstitution guide and the reconstitution calculator.

Research References

• The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin (Birk et al., J Am Soc Nephrol, 2013)
• Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy (Karaa et al., Neurology, 2018)
• Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial (Karaa et al., Neurology, 2023)
• Is an emerging pharmacotherapeutic era for rare mitochondrial diseases here? (Bedoyan and Vockley, Cell Metab, 2026)

Published research on SS-31 is indexed on PubMed. See our full UK buyer's guide for SS-31 and UK buyer's guide for SS-31 50mg.