SS-31

SS-31, also called elamipretide or MTP-131, is a small synthetic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH₂) developed by Hazel Szeto and Peter Schiller. It is one of the most-studied 'Szeto-Schiller' (SS) peptides — designed to selectively target and stabilize cardiolipin in the inner mitochondrial membrane. Unlike most peptides, SS-31 contains alternating aromatic and basic residues that give it a strong affinity for cardiolipin-rich membranes. It has been in multiple clinical trials for mitochondrial diseases, heart failure, and dry age-related macular degeneration. Research-grade SS-31 is sold strictly for laboratory use.

Mitochondria — the energy organelles inside your cells — have a unique inner membrane phospholipid called cardiolipin. With age, illness, or oxidative stress, cardiolipin gets damaged, and mitochondria stop making energy efficiently. SS-31 is a small peptide that selectively concentrates in the inner mitochondrial membrane, binds cardiolipin, and protects it from damage. The result in research is improved mitochondrial function, more efficient ATP production, and reduced oxidative stress.

SS-31 selectively binds cardiolipin in the inner mitochondrial membrane (with concentrations 1,000–10,000× higher in mitochondria than in cytoplasm). This binding stabilizes the electron transport chain supercomplexes, optimizes ATP production, and reduces electron leakage that generates reactive oxygen species. The net effect is restored mitochondrial efficiency in damaged cells.

• •Heart failure with preserved ejection fraction
• •Primary mitochondrial diseases (Barth syndrome, MELAS)
• •Dry age-related macular degeneration
• •Ischemia-reperfusion injury
• •Sarcopenia and age-related muscle decline
• •Renal mitochondrial dysfunction

SS-31 is a centerpiece of mitochondrial longevity discussion alongside MOTS-c, Humanin, and NAD+. Threads focus on its unique cardiolipin-targeting mechanism, the Stealth BioTherapeutics clinical program, and forum reports of improved energy and recovery on mitochondrial stacks.

“A bodyguard for mitochondrial cardiolipin.”

Most commonly combined with MOTS-c, Humanin, NAD+ precursors, and 5-Amino-1MQ in mitochondrial longevity stacks. Sometimes paired with CoQ10 and PQQ for additive mitochondrial support.

SS-31 (elamipretide) is a synthetic tetrapeptide that selectively binds cardiolipin in the inner mitochondrial membrane, stabilizing electron transport and improving ATP production. It is one of the most-studied mitochondrial-targeted peptides, with multiple clinical trials but not yet broadly approved.