SS-31 is a synthetic aromatic-cationic tetrapeptide from the Szeto-Schiller series, designed to concentrate at the inner mitochondrial membrane. It is studied as a research tool for mitochondrial function, particularly its interactions with the membrane phospholipid cardiolipin, and is one of the best-known examples of a rationally engineered organelle-targeting peptide.
What it is
SS-31's alternating aromatic and cationic residues give it an unusual property among short peptides: selective accumulation in mitochondria driven by the organelle's strong membrane potential. Its sequence design follows general amino acid sequence principles but is engineered for targeting, with non-natural residues detailed in its structure and synthesis article.
Why researchers study it
It is used to probe mitochondrial bioenergetics and oxidative-stress models, a space overlapping with cellular-energy tools like NAD+ in cellular research. Its proposed mechanism of action centers on cardiolipin binding and its downstream effects on membrane organization and electron transport.
How it compares to other mitochondrial tools
SS-31 is often discussed alongside the mitochondrial-derived peptide MOTS-c, but the two differ in how they reach and influence the organelle, making direct comparison a useful way to frame mitochondrial-peptide research.
Research context
Targeting peptides demand verified identity — see HPLC vs. mass spectrometry and how to read a COA — because small differences in composition can affect localization behavior.
Questions and experimental boundaries
SS-31 is most useful for asking how a cardiolipin-associated peptide changes mitochondrial behavior under a defined perturbation. It is not a general marker of mitochondrial abundance, and a change in one redox readout does not establish improved function across every bioenergetic parameter. Appropriate work measures localization, membrane state, respiration, and viability independently, with sequence controls that test whether the aromatic-cationic motif is necessary. Model choice matters because cardiolipin composition, respiratory demand, and membrane potential differ among cell types. These boundaries make the peptide a focused mechanistic probe rather than a universal proxy for mitochondrial health. The name elamipretide is commonly encountered in the literature, while SS-31 emphasizes the molecule’s origin in the Szeto-Schiller series. Regardless of naming, researchers should verify the stated sequence, salt form, and analytical identity of the material used. Comparisons across experiments are strongest when mitochondrial stressor, exposure timing, normalization strategy, and oxygen conditions are reported, since each can shift respiration and membrane-potential readouts.
Product page: SS-31 research vials.
Research Use Only. Supplied strictly for laboratory research and development — not for human or veterinary use, consumption, or any therapeutic or diagnostic purpose. This article is research education, not usage guidance.