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.