SS-31 Research Peptide: Complete Guide to Mitochondrial Targeting, Cardiolipin Binding, and Laboratory Applications
Research Notice: This article covers research on SS-31 research peptide and MOTS-C research peptide — available from Palmetto Peptides for laboratory use only.
Research Disclaimer: SS-31 is sold by Palmetto Peptides strictly as a research compound for in vitro and laboratory use only. It is not intended for human or veterinary consumption, administration, or therapeutic use.
SS-31 is a tetrapeptide research compound with the sequence D-Arg-Dmt-Lys-Phe-NH2 — the most widely studied member of the Szeto-Schiller peptide family, with a unique mechanism of action centered on mitochondrial accumulation and cardiolipin binding in laboratory models. Researchers can order SS-31 research peptide from Palmetto Peptides with lot-specific HPLC purity documentation, mass spectrometry identity confirmation, and peptide content data for every batch.
What Is SS-31 Research Peptide?
SS-31 (also known as elamipretide or MTP-131 in clinical research contexts) is a synthetic tetrapeptide developed by Dr. Hazel Szeto and Dr. Peter Schiller in the early 2000s. It was originally designed as a cell-permeable antioxidant, but subsequent research revealed that it selectively accumulates in mitochondria and binds to cardiolipin — the signature phospholipid of the inner mitochondrial membrane. This discovery repositioned SS-31 as one of the most mechanistically specific mitochondria-targeted research tools available.
For broader context on mitochondrial biology relevant to SS-31 research, see our guides on MOTS-C mitochondrial peptide research and mitochondrial function and aging research.
Molecular Identity: Sequence, Formula, and Key Properties
| Property | Value |
|---|---|
| Sequence | D-Arg-Dmt-Lys-Phe-NH2 |
| Molecular Formula | C32H49N9O5 |
| Molecular Weight | ~639.80 g/mol |
| Net Charge (pH 7.4) | +3 |
| CAS Number | 736992-21-5 |
| Also Known As | Elamipretide, MTP-131, Bendavia |
| Non-Standard Residue | 2',6'-Dimethyltyrosine (Dmt) at position 2 |
For a deep-dive on the chemical structure: SS-31 Chemical Structure: Sequence, Formula, and Molecular Weight.
Mechanism of Action in Laboratory Models
Step 1: Mitochondrial Accumulation
SS-31's net +3 charge at physiological pH, combined with the large negative membrane potential of the inner mitochondrial membrane (approximately -180 mV), creates a thermodynamic driving force for cationic compounds to concentrate inside mitochondria. SS-31 accumulates in mitochondria-rich compartments at concentrations estimated to be orders of magnitude above the bulk extracellular level.
Step 2: Cardiolipin Binding
Once at the inner membrane, SS-31 binds to cardiolipin via the aromatic-cationic interaction mechanism — electrostatic anchoring of cationic residues (D-Arg, Lys) to cardiolipin's anionic phosphate groups, combined with insertion of aromatic residues (Dmt, Phe) into the lipid acyl chain region. This localized binding distinguishes SS-31 from non-targeted antioxidant compounds. Full mechanism detail: SS-31 and Cardiolipin Interactions: What Laboratory Models Show.
Step 3: Downstream Effects in Cell-Based Models
In published in vitro studies, SS-31 treatment in stressed cell models has been associated with changes in cytochrome c behavior, mitochondrial membrane potential, electron transport chain activity, and ATP production. For assay design guidance: SS-31 In Vitro Mitochondrial Function Assay Applications.
Research Applications
SS-31 is used as a tool compound in laboratory models studying:
- Mitochondrial bioenergetics (Seahorse XF OCR analysis)
- Membrane potential (JC-1, TMRE fluorescence)
- Mitochondrial superoxide and ROS biology (MitoSOX)
- Cardiolipin biology and membrane dynamics
- Ischemia-reperfusion model systems in cardiac and renal cell lines
- Oxidative stress in neuronal cell models
- Mitochondria-mediated apoptosis pathway research
Related research context: NAD+ and mitochondrial biogenesis research, anti-aging and longevity peptide research, cellular health research.
Purity and Quality Standards
For rigorous in vitro research, SS-31 should meet the following minimum quality standards:
- HPLC purity: at least 95% for standard assays; 98% or above for quantitative or publication-quality work
- MS identity confirmation: lot-specific ESI-MS or MALDI-TOF data confirming MW approximately 639.80 g/mol
- Peptide content: reported separately from HPLC purity, accounting for TFA counterion and water
- Lot-specific COA with actual HPLC chromatogram included
For full QC guidance: HPLC Purity and Quality Control Standards for SS-31 and Analytical Methods for Verifying SS-31 Identity and Purity In-Lab.
Reconstitution and Storage
SS-31 is highly water-soluble (soluble at 10 mM or above in sterile water or PBS) due to its +3 net charge. Reconstitute in sterile ultrapure water or PBS pH 7.4. Avoid DMSO. Store lyophilized powder at -20C or -80C desiccated dark; reconstituted stocks in single-use aliquots at -80C. Maximum 3 freeze-thaw cycles. Full protocol: SS-31 Reconstitution and Long-Term Storage Protocols. Buffer formulation guidance: SS-31 Solubility, Stability, and Buffer Formulation Guidelines.
Purchasing SS-31 Research Peptide
Palmetto Peptides offers SS-31 research peptide with lot-specific HPLC and MS documentation. Key criteria to verify with any supplier: lot-specific COA, actual chromatogram (not just a number), MS identity confirmation, and peptide content percentage. Detailed guidance: Buying Guide: How to Select High-Quality SS-31 from Reputable Lab Suppliers. Order SS-31 research peptide from Palmetto Peptides here.
Complete SS-31 Research Cluster: All Supporting Articles
| Article | Topic |
|---|---|
| Chemical Structure: Sequence, Formula, Molecular Weight | Structural chemistry reference |
| Cardiolipin Interactions: What Lab Models Show | Mechanism deep-dive |
| In Vitro Mitochondrial Function Assays | Assay design and protocols |
| Reconstitution and Long-Term Storage Protocols | Lab handling procedures |
| SS-31 vs Other Szeto-Schiller Peptides | Analog comparison |
| HPLC Purity and Quality Control Standards | COA interpretation |
| Synthesis and Manufacturing Processes | Production overview |
| Solubility, Stability, and Buffer Formulation | Formulation guidance |
| History and Development of SS Peptides | Research origins |
| Buying Guide: Selecting a Reputable Supplier | Purchasing guidance |
| Analytical Methods for Identity and Purity Verification | In-lab QC methods |
| SS-31 FAQ for Scientists | Common questions answered |
Frequently Asked Questions
What is SS-31 research peptide?
SS-31 is a synthetic tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2. It is studied in laboratory settings for its mitochondria-targeting and cardiolipin-binding properties. Also known as elamipretide or MTP-131. Not approved for human or veterinary use — sold strictly as a research compound.
What does SS-31 do in mitochondrial research models?
In laboratory models, SS-31 accumulates in mitochondria driven by the inner membrane electrochemical potential, then binds cardiolipin via electrostatic and aromatic interactions. This has been associated in in vitro studies with changes in cytochrome c behavior, electron transport chain activity, and mitochondrial membrane potential.
What is the molecular weight of SS-31?
Approximately 639.80 g/mol. Molecular formula: C32H49N9O5. Monoisotopic mass: approximately 639.37 g/mol.
Is SS-31 approved for human use?
No. SS-31 (elamipretide) has not received FDA approval for any human therapeutic indication. It is available only as a research compound for qualified in vitro and laboratory use.
What purity grade should SS-31 have for research?
At least 95% HPLC purity for standard in vitro assays. 98% or above recommended for quantitative, dose-response, or publication-quality research. Always request a lot-specific COA with HPLC chromatogram and MS identity data.
How should SS-31 be stored?
Lyophilized SS-31 at -20C or -80C in desiccated dark environment. Reconstituted stocks at -80C in single-use aliquots, light-protected. Working solutions at 4C used within 24-48 hours.