SS-31 is a synthetic aromatic-cationic tetrapeptide studied in the literature for its interaction with mitochondrial membrane phospholipids. AminoOptimization Group supplies it as a lyophilised research powder in 10 mg and 50 mg presentations, tested to 99% purity by HPLC, with a Certificate of Analysis available for the lot supplied. This material is offered strictly for laboratory research use. It is not a drug, and it is not for human or veterinary use.
What is SS-31?
SS-31, referred to in some published work by the developmental code MTP-131, is a small synthetic peptide built from four amino acid residues arranged in an alternating aromatic-cationic pattern: D-arginine, 2′,6′-dimethyltyrosine, L-lysine, and phenylalaninamide. This alternation of a basic residue with an aromatic one is the structural feature the literature attributes to its capacity to concentrate in a specific membrane environment rather than distributing diffusely through the cell.
Unlike growth-factor-mimetic peptides that act at plasma-membrane receptors, SS-31 is described as a cell-permeable peptide that partitions into the inner mitochondrial membrane through electrostatic and hydrophobic interaction with cardiolipin, a phospholipid concentrated almost exclusively in that membrane. The D-configured N-terminal arginine and the C-terminal amidation are both noted in the literature as features that reduce susceptibility to proteolytic cleavage relative to a comparable all-L-amino-acid sequence, a property common to the broader Szeto-Schiller series of peptides to which SS-31 belongs.
Within that series, SS-31 is distinguished from earlier analogues such as SS-02 by the dimethyltyrosine substitution at position two. Published structure-activity work describes this substitution as conferring redox-active character on the tyrosine ring, which is offered as an explanation for differences in activity observed between series members in cell-free and cell-based assay systems.
Specifications
- Compound: SS-31
- CAS number: 736992-21-5
- Molecular formula: C32H49N9O5
- Molecular weight: 639.81 g/mol
- Purity: 99% HPLC
- Presentation: Lyophilised powder, sealed vial
- Available sizes: 10 mg, 50 mg
- Physical form: White to off-white powder
- Classification: Research peptide — not for human or veterinary use
Research context
Published research on SS-31 concentrates substantially on cardiolipin binding as the proposed mechanism underlying its accumulation at the inner mitochondrial membrane. Literature describes this interaction as stabilising cristae architecture and limiting formation of cardiolipin-cytochrome c complexes associated with peroxidase activity, a pathway implicated in reactive oxygen species generation in isolated mitochondria and cultured cell models.
The compound appears frequently in study designs modelling mitochondrial dysfunction: ischaemia-reperfusion protocols in isolated organ and cell preparations, oxidative stress induced by chemical uncouplers, and investigations of the mitochondrial permeability transition pore. Comparative work also examines electron transport chain efficiency and ATP synthesis capacity in tissue homogenates exposed to the peptide, with results typically reported as respiratory control ratios and oxygen consumption rates rather than any organism-level outcome.
None of this literature establishes safety or efficacy for use in humans. It is provided as research context only.
Reconstitution
Lyophilised peptide requires reconstitution with a suitable sterile diluent before use in solution. Bacteriostatic water is the diluent most commonly specified for multi-use laboratory preparations; sterile water is typical for single-use work.
Direct the diluent stream against the inner wall of the vial rather than onto the powder itself, and allow the material to dissolve without agitation. Peptides are susceptible to shear stress — do not shake the vial. Swirl gently if needed, and expect full dissolution within a few minutes at room temperature.
Working concentration is a function of how much diluent is added to a given vial mass. Our peptide reconstitution calculator computes the resulting concentration for any combination of vial size and diluent volume.
Storage and stability
Before reconstitution: store the sealed vial in a freezer at -20 °C, protected from light. Lyophilised peptide is comparatively stable in this state. Brief excursions to ambient temperature during shipping are normal and are not expected to compromise a properly lyophilised product.
After reconstitution: refrigerate at 2–8 °C and protect from light. Reconstituted peptide in solution is materially less stable than the dry powder. Avoid repeated freeze-thaw cycles, a well-documented cause of aggregation and loss of measurable potency — aliquot instead if repeated sampling is required.
Inspect solutions before use. Cloudiness, visible particulate, or discolouration indicate the material should not be relied upon for quantitative work.
Certificate of Analysis
Every lot is tested by high-performance liquid chromatography, and the purity figure shown above refers to analytical results for the specific lot supplied — not to a generic specification. A Certificate of Analysis is available on request, and we will provide lot-specific documentation before purchase if your protocol requires it.
Purity by HPLC describes the proportion of the target peptide relative to detectable related substances. It is a statement about the material as manufactured and tested. It is expressly not a representation that the material is suitable for any use in humans or animals.
Handling and safety
Handle in accordance with good laboratory practice. Use appropriate personal protective equipment, work in a suitable containment environment, and dispose of material and consumables according to your institution’s requirements and applicable local regulation. Anyone with access to this material should understand that it is not for human or veterinary use.
Frequently asked questions
What distinguishes SS-31 from other mitochondria-targeted peptides?
SS-31 is characterised by its alternating aromatic-cationic residue pattern, which the literature links to selective partitioning into the inner mitochondrial membrane via cardiolipin binding. Other peptides in the same developmental series carry different substitutions at the aromatic position and are reported to show different activity profiles in comparable assays.
Is SS-31 approved in Canada?
No. This compound has not been evaluated or authorised by Health Canada, the FDA, or any comparable regulatory authority. It carries no DIN or NPN, its safety and efficacy for human use have not been assessed, and it is supplied for laboratory research only.
How much diluent should be used for reconstitution?
That depends on the working concentration your protocol requires. Use the reconstitution calculator to work out the resulting concentration for your vial size.
How long is reconstituted SS-31 stable in solution?
Stability in solution is shorter than in lyophilised form and depends on diluent, temperature, and handling. Refrigerate at 2–8 °C, protect from light, avoid freeze-thaw cycling, and validate stability for your own storage conditions if your work depends on it.
Do you provide a Certificate of Analysis?
Yes — lot-specific, available on request, including before purchase.
Research use only
This product is supplied solely for laboratory and scientific research. It is not a drug, food, cosmetic, or medical device, and it must not be administered to humans or animals. Nothing on this page is medical advice or a therapeutic claim. Full terms are set out in our Research Use Only Disclaimer.
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