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Mitochondrial compounds & coenzymes · 4 amino acids · CAS 736992-21-5

SS-31, Elamipretide

A four-residue mitochondria-targeted Szeto-Schiller peptide, also known as elamipretide, supplied as a lyophilised research powder in 10 mg and 50 mg vials with an independent HPLC and LC-MS certificate published for every batch.

Vial size
£30.00BK-SS31-10 · Out of stock

For in-vitro research use only. Not for human or veterinary use. 18+.

Certificate of analysisLot BK-SS31-10
SS-31 10 mg
Purity, RP-HPLC, 220 nm
99.76 %
Laboratory
Janoshik
Signed report (PDF)Batch page

About SS-31

Written for laboratory researchers from the published literature. Not medical advice; nothing on this page describes use in humans or animals.

What SS-31 is

SS-31 is a synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2',6'-dimethyltyrosine and the C-terminus is amidated. It belongs to the family of Szeto-Schiller peptides designed by Hazel Szeto and Peter Schiller, who were investigating short, aromatic-cationic sequences and found that this one concentrated in mitochondria rather than at the opioid receptors they had originally been studying. The alternating pattern of basic and aromatic residues is what carries the molecule across membranes and into the inner mitochondrial membrane, where it is reported to bind the phospholipid cardiolipin.

The compound was later developed by Stealth BioTherapeutics under the code MTP-131 and is known by the non-proprietary name elamipretide. The D-arginine at the first position and the dimethylated tyrosine make it resistant to aminopeptidases, which is why a sequence of only four residues has a useful lifetime in biological preparations. The average molecular weight is approximately 640 g/mol and the CAS number is 736992-21-5.

The published literature on the compound, with references, is collected in the monograph.

What you receive

Each vial contains SS-31 as a white to off-white lyophilised powder, sealed with a flip-off cap over a crimped stopper, in the net quantity stated on the label: 10 mg or 50 mg. The peptide is supplied as an acetate salt, with no carrier, mannitol or other excipient unless the batch certificate says otherwise. The batch number is printed on the label and matches the certificate in our register.

Reading the certificate for an SS-31 batch

Purity by reversed-phase HPLC is reported as the area of the main peak against all peaks and should be above 99% for a tetrapeptide. Identity by LC-MS is reported as the observed mass against the expected mass of about 640 Da for the protonated molecule. The point to check is that the mass corresponds to the dimethylated tyrosine rather than plain tyrosine, a difference of 28 Da. Net peptide content gives the milligrams of peptide actually in the vial after allowing for water and the acetate counter-ion.

The impurities occasionally seen are the free acid form, where the C-terminal amide has been lost, and traces of residual trifluoroacetate from purification if the salt exchange was incomplete. Our guide to reading a certificate of analysis shows annotated examples, and HPLC and LC-MS explained describes the methods behind the figures.

Storage and handling

Sealed vials should be kept refrigerated at 2 to 8 °C and protected from light; −20 °C is preferable for storage beyond a few months, and the lyophilised powder is stable for well over a year under those conditions. Small cationic peptides supplied as acetate salts are hygroscopic, so allow the vial to reach room temperature before opening and reseal promptly after weighing. SS-31 dissolves readily in water or bacteriostatic water to give a clear, colourless solution. Solutions are reasonably stable refrigerated for short periods but should be aliquoted and frozen for longer work; the storage and stability guide covers solvents, concentrations and freeze-thaw behaviour.

Specification

Reference values pending verification against the batch certificate.

CAS number
736992-21-5
Molecular formula
C32H49N9O5
Molecular weight
639.8 g/mol
Sequence
D-Arg-Dmt-Lys-Phe-NH2
Appearance
White to off-white lyophilised powder
Purity
≥99% by RP-HPLC, per batch certificate
Net content
10 mg, 50 mg
Storage, sealed
2–8 °C short term; −20 °C or below long term; protect from light; avoid freeze–thaw cycles
Storage, reconstituted
2–8 °C; use within the period stated in the compound monograph
Research use
In-vitro laboratory research only

Questions about SS-31

Is SS-31 the same compound as elamipretide?

Yes. SS-31 is the laboratory designation given by Szeto and Schiller to the fourth peptide in their series, and elamipretide is the international non-proprietary name adopted when Stealth BioTherapeutics developed it under the code MTP-131. All three names refer to the same tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2, and the certificate confirms identity against that structure.

What is Dmt and why does it matter for the certificate?

Dmt is 2',6'-dimethyltyrosine, a non-natural amino acid in which both positions flanking the phenolic hydroxyl carry a methyl group. It is the residue that distinguishes SS-31 from a plain tyrosine-containing sequence, and it adds 28 Da to the expected mass. A batch made with ordinary tyrosine would show a mass of about 612 rather than 640, which is one reason the LC-MS result is worth reading.

Why 10 mg and 50 mg vials?

SS-31 is a light molecule of roughly 640 g/mol, so even 10 mg represents a large molar quantity and covers an extended series of isolated-mitochondria or cell-culture experiments. The 50 mg vial lowers the per-milligram cost for laboratories running the peptide across many plates or over several months. Both sizes come from batches with their own published certificate.

How is SS-31 used in the published in-vitro work?

The literature mostly reports it in isolated mitochondrial preparations and cultured cells, where it is described as accumulating in the inner mitochondrial membrane through its affinity for cardiolipin. Reported readouts include cytochrome c peroxidase activity, membrane potential, oxygen consumption and reactive oxygen species. Concentrations are given in the primary papers and the monograph; nothing here describes use outside the laboratory.

What is in the vial?

SS-31 as a white to off-white lyophilised powder, sealed under nitrogen, in the net quantity stated on the label. No carrier, no excipient unless the certificate says otherwise.

Which batch will I receive?

The batch shown in the certificate panel for the size you choose. Its number is printed on the vial and on your dispatch note, and its full report is on the batch page.

How is purity measured?

By reversed-phase HPLC at an independent laboratory, reported as the area of the main peak against all peaks. Identity is confirmed by LC-MS against the expected mass.

How should the sealed vial be stored?

2–8 °C short term; −20 °C or below long term; protect from light; avoid freeze–thaw cycles

When is my order dispatched?

Same day for orders placed before 3pm, Monday to Saturday, by Royal Mail Tracked 24. Delivery is free.

Who may buy?

Researchers and institutions aged 18 or over, for in-vitro laboratory use under our terms. Nothing we sell is for human or veterinary use.

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