SS-31: Form, Reconstitution and Laboratory Storage

Physical form

SS-31 (elamipretide) ships as a white to off-white lyophilized powder in a sealed glass vial, typically 10 mg of peptide. The lyophilizate is hygroscopic, so the vial is opened only after it has equilibrated to room temperature, this prevents moisture condensing on cold glass.

Reconstitution chemistry

The peptide is readily water-soluble. Reconstitution uses sterile or bacteriostatic water (the latter contains ~0.9% benzyl alcohol, suitable for repeated sampling). Add the diluent slowly, directing the stream against the vial wall rather than onto the peptide pellet. Do not shake the vial: swirl gently or let it stand until fully dissolved. Vigorous agitation creates foam and local air-water interfaces where peptides denature and aggregate. Because SS-31 is cationic and water-soluble, organic co-solvents are usually unnecessary.

Concentration math is direct: 10 mg in 2 mL gives 5 mg/mL; in 1 mL, 10 mg/mL. Choose the volume to match the assay's working concentration.

Storage: lyophilizate versus solution

The sealed lyophilized peptide is most stable: kept cold (−20 °C for long-term), protected from light and moisture, it retains its properties for months. The reconstituted solution is markedly less stable, keep it refrigerated (2–8 °C) and use within a short window of days. For longer storage, aliquot and freeze the solution, avoiding repeated freeze-thaw cycles that mechanically damage the peptide.

Stability and quality control

The main degradation routes are hydrolysis, oxidation and surface aggregation. The N-terminal D-arginine improves proteolytic resistance relative to all-L analogs but does not protect against chemical oxidation or foaming. Because of the uncommon D-Arg residue, some suppliers substitute the cheaper L-isomer, so independent analysis (HPLC for purity, mass spectrometry for mass/sequence) is a sensible incoming control.

Research applications

SS-31 is used as a chemical tool in models of mitochondrial bioenergetics, oxidative stress and ischemia-reperfusion, on isolated mitochondria, cell cultures and animal models. The material is intended for laboratory research use only (RUO) and not for human use.

A full review of the mechanism and clinical data is available in the monograph.