SS-31

SS-31 is a synthetic, cell-penetrating tetrapeptide developed by Hazel Szeto and Peter Schiller. It has the amino acid sequence D-Arg-2′,6′-dimethyltyrosine-Lys-Phe-NH2, and its alternating cationic and aromatic residues give it a strong affinity for the inner mitochondrial membrane.

Unlike conventional antioxidants that distribute non-specifically throughout the cell, SS-31 selectively concentrates in mitochondria by binding to cardiolipin, a phospholipid found almost exclusively on the inner mitochondrial membrane. By stabilizing cardiolipin, it is studied for its role in preserving cristae structure, supporting electron transport chain function, and reducing the production of reactive oxygen species.

In preclinical and clinical research, SS-31 has been investigated across conditions linked to mitochondrial dysfunction, including age-related muscle decline, heart failure, neurodegeneration, and rare primary mitochondrial diseases. The inclusion of D-amino acids and an amidated C-terminus increases its resistance to enzymatic degradation.

Research-grade SS-31 is sold strictly for laboratory and research purposes only.