SS-31 (Elamipretide)

SS-31 (Elamipretide; D-Arg-Dmt-Lys-Phe-NH2; CAS 736992-21-5; MW 639.8 g/mol) is a D-amino acid tetrapeptide designed to selectively target the inner mitochondrial membrane (IMM) by electrostatic interaction with cardiolipin — a phospholipid critical to cristae structure and electron transport chain efficiency. SS-31 accumulates at ~10,000× greater concentration at the IMM than in cytoplasm, where it reduces mitochondrial ROS production, stabilizes cardiolipin against peroxidation, and prevents the cristae remodeling that impairs ATP synthesis in aging and disease. Phase II clinical trials in heart failure (PROGRESS-HF) and Barth syndrome document meaningful mechanistic engagement in humans.

This mitochondria-targeted peptide functions through a unique cardiolipin-binding mechanism, concentrating specifically at the inner mitochondrial membrane where it exerts protective effects on mitochondrial structure and function. The D-amino acid configuration, particularly D-Arg, provides exceptional proteolytic stability and enables the peptide to reach mitochondrial targets without degradation. The dimethyltyrosine (Dmt) residue serves as the active site for ROS scavenging and cardiolipin interaction.

In research applications, SS-31 demonstrates ability to preserve mitochondrial cristae architecture, reduce reactive oxygen species production at the source, and maintain electron transport chain efficiency under stress conditions. By stabilizing cardiolipin — the signature phospholipid of the inner mitochondrial membrane — SS-31 prevents the membrane remodeling and permeability changes that characterize mitochondrial dysfunction in aging, neurodegeneration, and metabolic disease.

The peptide's selective accumulation in mitochondria (10,000:1 ratio vs. cytoplasm) makes it an exceptionally precise research tool for investigating mitochondrial-specific interventions without off-target cytoplasmic effects. Clinical trials in heart failure and mitochondrial diseases provide human translational data supporting its mechanism of action.