SS-31 Research Peptide: Complete Guide to Mitochondrial Targeting, Cardiolipin Binding, and Laboratory Applications

Aubrey Walker

April 21, 2026

ss-31complete guidemitochondriacardiolipinresearch peptides

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 Use Only Disclaimer: All peptides listed on this page are sold exclusively for in vitro and legitimate laboratory research purposes. They are not intended for human consumption, veterinary use, or any clinical application. The information in this article is for scientific and educational reference only and does not constitute medical advice. All research use must comply with applicable federal, state, and institutional regulations. Palmetto Peptides complies fully with all applicable FDA guidelines.

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.

Last Updated: April 21, 2026 | Reading Time: Approximately 7 minutes | Author: Palmetto Peptides Research Team

Quick Answer

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.

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

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.