SS-31, also known as elamipretide, is a synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2. Molecular formula C32H49N9O5, molecular weight 639.78 g/mol.
Two features of that short sequence are deliberate design rather than incidental. The N-terminal arginine is the D-isomer, and position two is 2,6-dimethyltyrosine — a non-standard residue. Both choices confer resistance to peptidase cleavage, which a sequence of four natural L-amino acids would not survive.
Research context
SS-31 belongs to a class described as mitochondria-targeting peptides. The alternating aromatic-cationic motif allows the molecule to cross cell membranes without a transporter and accumulate in the inner mitochondrial membrane, where published work reports it associates with cardiolipin — a phospholipid largely confined to that membrane and closely tied to the organisation of the electron transport chain.
The research interest lies in that targeting mechanism as much as in any downstream endpoint. Delivering a compound selectively to a subcellular compartment is a hard problem, and SS-31 is studied partly as a demonstration that it can be done with a four-residue peptide. Published work examines mitochondrial respiration, reactive oxygen species production, and cardiolipin-associated cristae structure in model systems.
For a fuller treatment of the sequence, published models and technical data, see the SS-31 research guide.
Specification
CAS number 736992-21-5. Supplied as a white lyophilized powder, soluble in water. This batch assayed at 99.71% purity, verified by HPLC and LC-MS at ILS Lab.
Handling
Reconstitute with bacteriostatic or sterile water, introducing the diluent against the vial wall and swirling gently rather than shaking. Store lyophilized at −20°C protected from light; refrigerate at 2–8°C once reconstituted.
Ships with a batch-specific Certificate of Analysis. Cross-check the batch ID printed on your vial against the CoA before use — see the guide to reading a CoA if you are unfamiliar with the format.
Frequently asked questions about SS-31
How does SS-31 reach the mitochondria?
Through its alternating aromatic-cationic motif. That structural pattern allows the molecule to cross cell membranes without requiring a transporter, and the cationic charge favours accumulation in the inner mitochondrial membrane, which carries a strong negative potential. Published work reports it then associates with cardiolipin, a phospholipid largely confined to that membrane. Selective delivery to a subcellular compartment is a hard problem, and doing it with four residues is much of why the compound is studied.
Why does SS-31 contain non-standard amino acids?
Survival. A four-residue peptide of natural L-amino acids would be cleaved almost immediately by peptidases. The D-isomer arginine at position one and 2,6-dimethyltyrosine at position two both resist enzymatic cleavage — the same design principle used in PT-141 and MT-II, applied here to an unusually short sequence.
What is cardiolipin and why does it matter?
A phospholipid found almost exclusively in the inner mitochondrial membrane, where it is closely tied to the organisation of the electron transport chain and to cristae structure. Because it is essentially confined to that one location, a compound that associates with cardiolipin is by definition mitochondria-localised. Published work on SS-31 examines respiration, reactive oxygen species production and cristae morphology through that association.
How is SS-31 stored and handled?
Bacteriostatic or sterile water for reconstitution; it is water-soluble. Introduce the diluent against the vial wall and swirl gently rather than shaking. Store lyophilized at −20°C protected from light; refrigerate at 2–8°C once reconstituted. The non-standard residues make this a relatively robust peptide against enzymatic degradation, but standard storage precautions still apply.
Research use only. Not for human or veterinary use, not for use in diagnostic procedures, and not evaluated by the U.S. Food and Drug Administration.
