SS-31: Mitochondrial Membrane Stabilization Research
PeptaBase Research Review | 2026-03-04
What Is SS-31?
SS-31 (brand name Elamipretide) is a four-amino-acid peptide-D-Arg-Dmt-Lys-Phe-NH2-designed to cross cell membranes and target mitochondria. Hazel Szeto and Peter Schiller developed the SS peptide family specifically for this. SS-31's positive charge lets it accumulate inside the inner mitochondrial membrane, reaching concentrations much higher there than elsewhere in the cell.
Cardiolipin Binding and the Inner Mitochondrial Membrane
SS-31 works by binding to cardiolipin, a phospholipid that sits almost exclusively in the inner mitochondrial membrane. Cardiolipin does three key jobs: it stabilizes electron transport chain complexes (Complexes I-V), maintains cristae shape, and helps ATP synthase assemble.
When you age or get stressed, cardiolipin falls apart-it gets oxidized and repositioned. This breaks the electron transport chain, kills ATP production, and can trigger cell death pathways.
SS-31 grabs onto cardiolipin and protects it. The binding is both electrostatic and hydrophobic, which stabilizes cardiolipin against oxidation, preserves cristae structure, and keeps the electron transport chain functional. By saving cardiolipin, SS-31 keeps mitochondria working when they'd otherwise fail.
Cardiac Dysfunction and Heart Failure Research
Researchers have tested SS-31 heavily in heart disease models. In ischemia-reperfusion injury (heart attack and reperfusion damage), SS-31 reduces infarct size, preserves mitochondrial potential, and cuts oxidative stress. It blocks the mitochondrial permeability transition pore (mPTP) opening that happens during reperfusion-a key driver of damage.
In heart failure models with pressure overload and reduced ejection fraction, SS-31 improved ventricular function, reduced scarring, and kept mitochondrial structure intact. This makes sense given its mechanism: it improves energy production in the energy-hungry heart.
Aging Models
Since mitochondrial dysfunction drives aging, researchers tested SS-31 in old animals. Studies found it improved skeletal muscle mitochondrial function, reduced sarcopenia (age-related muscle loss), and boosted exercise capacity. The logic: cardiolipin breaks down with age, so fixing it should reverse mitochondrial decline.
FDA Clinical Trial Context: Barth Syndrome
SS-31 (Elamipretide) has reached human trials. Barth syndrome-a rare genetic disorder where cardiolipin remodeling goes wrong-was the natural target given SS-31's mechanism. Trials in Barth patients tested cardiac function and exercise capacity. Results were mixed on primary endpoints, but trials confirmed safety and gave useful human pharmacokinetic data. Stealth BioTherapeutics also ran trials in heart failure with reduced ejection fraction (HFrEF).
--- For research use only. Not medical advice.