SS-31

Relevance to Vision Research

Retinal ganglion cells and foveal photoreceptors carry one of the highest mitochondrial densities in the human body. SS-31 is studied in vision research precisely because it concentrates at mitochondrial cardiolipin.

An animated map of the visual pathway, from the eye through the brain to the systemic processes of aging. Highlighted nodes mark the structures SS-31 is studied against.

Illustrative research map : highlighted structures reflect the published in-vitro / preclinical literature, not human outcomes.

Summaries of observations reported in published in-vitro and preclinical research. These are research-model findings, not established human outcomes, and not claims of benefit, safety, or efficacy. Supplied for laboratory research use only.

The problem SS-31 was designed around

Mitochondria do not generate energy across a flat surface. The inner membrane folds into dense pleats called cristae, and the folding is what makes the chemistry work: it packs an enormous amount of respiratory machinery into a small volume and holds the electron-transport complexes close enough together to hand electrons along efficiently.

Holding that geometry is the job of cardiolipin, an unusual four-tailed phospholipid found almost nowhere else in the cell. Cardiolipin is also chemically fragile. Its tails are polyunsaturated, it sits directly beside the respiratory chain where reactive oxygen species are produced, and when it oxidises the cristae lose their shape. The literature describes a self-reinforcing loop: oxidised cardiolipin means looser cristae, looser cristae mean less efficient electron transfer, and less efficient transfer means more leakage.

SS-31 is an aromatic-cationic tetrapeptide designed to concentrate at that membrane. Its alternating charged and aromatic residues, including a non-standard 2,6-dimethyltyrosine, let it associate with cardiolipin without collapsing the membrane potential the way most cationic molecules would.

Why vision researchers keep returning to it

The retina is an unusually demanding place to be a mitochondrion. Photoreceptor inner segments and retinal ganglion cell axons carry some of the highest mitochondrial densities in the body, and the retina combines that load with intense light exposure, high oxygen tension, and membranes rich in exactly the polyunsaturated fats that oxidise first.

That combination is why elamipretide has been investigated in retinal contexts, including study programmes in dry age-related macular degeneration and geographic atrophy, and in preclinical diabetic retinopathy models. Our own literature synthesis on this sits in the science notes, and the structural work on how the peptide sits against the cardiolipin interface is written up separately.

None of that work establishes a human outcome, and the clinical programmes are the property of the sponsors who ran them. What it does explain is why this particular tetrapeptide shows up so often in retinal bioenergetics assays.

What this vial is for

Catalogued as a sequence-defined peptide reference standard for mitochondrial and phospholipid interaction work: membrane association assays, cardiolipin binding studies, cristae morphology imaging, and respiratory-chain assays in cultured cells and isolated mitochondria.

Identity is confirmed by LC-MS and purity by HPLC against a ≥99% specification. The non-canonical Dmt residue makes identity confirmation worth doing rather than assuming, since it is the residue most likely to be substituted in poorly made material.

Why It Is Used

Molecular Identity

CAS Number

736992-21-5

Molecular Formula

C₃₂H₄₉N₉O₅

Molecular Weight

639.79 g/mol

Sequence

H-D-Arg-Dmt-Lys-Phe-NH₂ (Dmt = 2,6-dimethyltyrosine)

Purity

≥ 99.0% (HPLC, area)

Format

Lyophilized powder, vacuum-sealed vial

Analytical Specification

Research Context

SS-31 (elamipretide) is an aromatic-cationic tetrapeptide widely studied for its association with cardiolipin in the inner mitochondrial membrane and its reported effects on electron-transport-chain organization in in-vitro and preclinical models. It incorporates a non-canonical 2,6-dimethyltyrosine (Dmt) residue. Catalogued here as a peptide reference standard for mitochondrial and phospholipid interaction assays.