SS-31 (Elamipretide) is a synthetic, water-soluble tetrapeptide (composed of four amino acids) originally developed at Cornell University. This novel compound is classified as a Mitochondria-Targeting Peptide (MTP), meaning it is engineered to easily cross cell membranes and accumulate selectively at high concentrations within the mitochondria. The peptide’s structure—specifically the sequence D-Arg-Dmt-Lys-Phe-NH2—is the source of its high permeability and potent action, making it a unique therapeutic candidate for treating age-related diseases associated with mitochondrial dysfunction.