What it is
SS-31, also called elamipretide, is a tetrapeptide designed around a specific structural pattern: alternating basic and aromatic residues. The sequence is D-arginine, dimethyltyrosine, lysine, phenylalanine, with a C-terminal amide.
Two of those four are not standard protein residues. D-arginine is the mirror image of the natural form, and 2,6-dimethyltyrosine carries two methyl groups on its aromatic ring that ordinary tyrosine does not have.
| Property | Value | Where it is confirmed |
|---|---|---|
| Residue count | 4 (D-Arg, Dmt, Lys, Phe-NH2) | Synthesis record |
| Approximate mass | near 640 g/mol | Certificate of analysis |
| Non-standard residues | D-arginine; 2,6-dimethyltyrosine | Synthesis record |
| C-terminus | Amide | Synthesis record; identity result |
| Physical form supplied | Lyophilized solid | Label and batch record |
Why a standard table gives the wrong answer
Anyone computing this compound's mass from a table of the twenty protein amino acids will be wrong twice over. Dimethyltyrosine is about 28 units heavier than tyrosine — two methyl groups — and it is not in any standard table, so a calculator will either substitute plain tyrosine or fail silently. The C-terminal amide subtracts about one further unit relative to a free acid.
The rule established under Ipamorelin applies with full force: for a modified peptide, the calculated mass on the report is the reference, and the stated molecular formula is what makes it interpretable. A disagreement with your own arithmetic is usually a fact about the arithmetic.
What the D-residue hides, and what catches it
D-arginine has exactly the same mass as L-arginine. If the wrong stereoisomer were incorporated, no mass measurement would object — the molecule would weigh precisely what it should. Diastereomers do generally separate under reversed-phase conditions, so the wrong isomer usually appears as a distinct peak near the main one, which means the chromatogram is the instrument that catches this error and the mass result is not.
Where identity is reported as HPLC-RTM, retention-time matching against a properly characterised reference standard is doing exactly this work — provided the report names the standard it matched against.
What else the sequence predicts
- Four residues is a very short synthesis. Deletion sequences are few and easily resolved, so purity figures are typically high and a low one is informative rather than routine — the same inversion described under Epitalon.
- Strongly basic. Arginine and lysine give the molecule a high positive charge, which can produce peak tailing on a reversed-phase column and make a purity figure less trustworthy than its magnitude suggests.
- No cysteine, no methionine. Oxidation is not the primary degradation route.
Storage of the lyophilized solid
Supplied as a freeze-dried solid, governed by temperature and moisture. Strongly basic peptides are markedly hygroscopic, so equilibration to room temperature before opening a vial is worth observing.
Stability is a documented property rather than an assumed one: a laboratory establishes it by holding material under defined conditions and re-analysing at intervals. Where a retest date is stated, the question worth asking is what data supports it. See storing lyophilized research materials.
What the published literature covers
The research record is preclinical and clinical in parts, covering mitochondrial membrane interactions, cell-culture studies of mitochondrial function, and animal models. The alternating basic-aromatic motif described above is itself the subject of a substantial part of that literature, which is why the structure rather than the compound's effects is the substance of this page.
The compound has not completed the regulatory process that would establish safety or efficacy for any medical indication, and findings in animal models and cell culture do not transfer automatically to other species. Arctic Lab Supply does not publish research conclusions, recommend applications, or provide guidance on experimental design.