What Is SS-31 Peptide?

SS-31 peptide is a synthetic mitochondria-targeted tetrapeptide that has been extensively investigated in mitochondrial biology, membrane biophysics, cardiolipin research, and mitochondrial bioenergetics.

SS-31 is also known as elamipretide and MTP-131. Its chemical structure is commonly represented as D-Arg-Dmt-Lys-Phe-NH₂, where Dmt refers to 2,6-dimethyltyrosine. PubChem identifies the parent compound with molecular formula C₃₂H₄₉N₉O₅, molecular weight 639.8 g/mol, and calculated exact mass 639.38566570 Da.

The peptide has attracted scientific interest because of its reported interaction with cardiolipin, a distinctive phospholipid found predominantly in the inner mitochondrial membrane. Experimental studies have investigated SS-31 interactions with cardiolipin-containing membranes, mitochondrial proteins, membrane electrostatics, and respiratory processes.

For researchers evaluating SS-31 peptide material, chemical identity and analytical documentation are therefore important. Molecular-weight information, HPLC data, mass spectrometry, purity testing, lot identification, and a batch-specific Certificate of Analysis can help establish whether a research material corresponds to its stated specifications.

Important distinction: SS-31/elamipretide is now also the active ingredient in the FDA-approved prescription drug FORZINITY for a specific Barth syndrome indication. That approval applies to the approved pharmaceutical product and labeled indication; it should not be used to imply that every material sold as “SS-31 peptide” is the FDA-approved drug product.

SS-31 Peptide at a Glance

Property	SS-31 / Elamipretide
Common research name	SS-31
Generic name	Elamipretide
Other identifier	MTP-131
Peptide class	Synthetic tetrapeptide
Chemical sequence	D-Arg-Dmt-Lys-Phe-NH₂
Sequence representation	RXKF
Molecular formula	C₃₂H₄₉N₉O₅
Molecular weight	639.8 g/mol
Exact mass	639.38566570 Da
Monoisotopic mass	639.38566570 Da
Research focus	Mitochondrial biology
Important membrane lipid	Cardiolipin

PubChem reports the molecular properties above for parent elamipretide.

SS-31 Peptide Sequence and Structure

The SS-31 peptide sequence is commonly represented chemically as:

D-Arg-Dmt-Lys-Phe-NH₂

PubChem uses the compact sequence representation RXKF, reflecting the modified tyrosine residue within the molecule.

The presence of charged amino-acid residues together with aromatic components is relevant to the peptide’s interaction with biological membranes.

Research using membrane models has investigated how SS-31 partitions into membrane interfaces and interacts with negatively charged lipid environments. A peer-reviewed study found that SS-31 interacts with cardiolipin-containing membranes and modulates membrane surface electrostatics without destabilizing lamellar bilayers under the experimental conditions studied.

This makes SS-31 particularly interesting for researchers studying:

Mitochondrial membrane biology
Cardiolipin interactions
Membrane biophysics
Peptide-lipid interactions
Mitochondrial protein interactions
Bioenergetics
Oxidative phosphorylation

SS-31 Molecular Weight

The molecular weight of parent SS-31/elamipretide is:

639.8 g/mol

PubChem reports a calculated exact mass of:

639.38566570 Da

The listed monoisotopic mass is also 639.38566570 Da.

These values are useful when planning analytical characterization or comparing an SS-31 research material with expected molecular properties.

Molecular weight can be particularly relevant for:

LC-MS analysis
High-resolution mass spectrometry
Peptide identity confirmation
Analytical method development
Reference-material comparison
Laboratory documentation
Research database searches

Researchers should be careful when comparing molecular masses across different formulations. Parent elamipretide and salt or counterion-containing forms can have different molecular weights.

For example, an elamipretide TFA form has a different calculated molecular weight from the parent compound. Therefore, the expected mass should always be matched to the precise chemical form being analyzed.

SS-31 Exact Mass and Mass Spectrometry

For analytical laboratories, exact mass is often more useful than rounded molecular weight when evaluating peptide identity.

For parent SS-31/elamipretide:

Exact mass: 639.38566570 Da

Monoisotopic mass: 639.38566570 Da

LC-MS or high-resolution mass spectrometry can provide molecular-level information that complements chromatographic testing.

A laboratory investigating SS-31 may evaluate multiple parameters rather than relying exclusively on mass:

Expected molecular mass
Observed mass-to-charge ratio
Isotope distribution
Chromatographic retention time
Main peak area
Secondary chromatographic peaks
Sample preparation
Analytical method conditions

This multi-parameter approach can provide a more informative assessment of peptide identity and analytical quality.

SS-31 and Mitochondrial Research

One of the largest research areas surrounding SS-31 involves mitochondrial biology.

Mitochondria contain specialized membranes that support oxidative phosphorylation and other cellular processes. Cardiolipin is an important component of the inner mitochondrial membrane, and SS-31 has been investigated because of its interaction with cardiolipin.

Research has reported that SS-31 can interact with cardiolipin-containing membranes and influence membrane surface electrostatics.

Other research has examined SS-31 interactions with mitochondrial proteins using chemical cross-linking and mass spectrometry. Investigators identified SS-31-associated proteins connected with cardiolipin and pathways involved in oxidative phosphorylation and metabolism.

This creates a broad scientific keyword cluster around SS-31 peptide:

SS-31 mitochondrial research
SS-31 cardiolipin
SS-31 mitochondrial membrane
SS-31 bioenergetics
SS-31 oxidative phosphorylation
SS-31 peptide research
elamipretide mitochondrial research

SS-31 and Cardiolipin Research

Cardiolipin is central to much of the scientific discussion surrounding SS-31.

Cardiolipin is a distinctive phospholipid associated with the mitochondrial inner membrane. Its unusual structure and localization make it an important subject in mitochondrial membrane research.

Experimental studies have reported selective interactions between SS-31 and cardiolipin-containing membrane systems. One study found that SS-31 interacts with cardiolipin and affects its interaction with cytochrome c, with experimental measurements involving electron-transfer processes and mitochondrial oxygen consumption.

More recent mechanistic research continues to investigate how elamipretide-cardiolipin interactions may affect mitochondrial membrane properties and protein organization.

For SEO purposes, this makes “SS-31 cardiolipin research” an important semantic supporting topic for an SS-31 peptide pillar page.

SS-31 Peptide Purity

SS-31 peptide purity is a critical consideration when evaluating a research material.

A product’s stated purity should ideally be supported by batch-specific analytical documentation rather than relying solely on a product description.

Common analytical documentation may include:

HPLC chromatogram
Reported chromatographic purity
LC-MS results
Molecular-mass information
Lot number
Batch number
Testing date
Certificate of Analysis
Analytical method information

HPLC purity is method-dependent. A reported percentage represents the chromatographic result obtained under the stated analytical conditions and should not automatically be interpreted as absolute purity under every possible analytical technique.

For demanding laboratory workflows, researchers may combine chromatography and mass spectrometry with other appropriate analytical methods.

SS-31 HPLC Analysis

HPLC analysis is an important keyword and quality-control topic for SS-31 research materials.

High-performance liquid chromatography can separate components within a sample and provide a chromatographic profile.

A typical SS-31 HPLC report may show:

Main SS-31 peak
Retention time
Relative peak area
Secondary peaks
Reported purity
Analytical method
Sample identification

When reviewing HPLC documentation, researchers should verify that the chromatogram corresponds to the same lot or batch of SS-31 peptide being evaluated.

A chromatogram without identifiable batch information provides less useful traceability than a complete, lot-specific analytical report.

SS-31 COA: Certificate of Analysis Guide

A Certificate of Analysis (COA) provides batch-level information about a material.

When reviewing an SS-31 peptide COA, researchers can look for several core elements.

Product identity

The material should be clearly identified as SS-31, elamipretide, or the applicable chemical designation.

Lot number

The lot number should match the material supplied.

Purity

The reported purity should identify the analytical method used where appropriate.

Molecular mass

The documented molecular mass should correspond to the intended chemical form.

Testing information

The COA should identify relevant analytical procedures and results.

Date of analysis

A testing date helps establish the provenance of the analytical document.

Supplier or laboratory identification

The organization responsible for the analysis should be identifiable.

A COA is valuable documentation, but researchers should interpret it within their laboratory’s own quality-control framework.

SS-31 Research Applications

SS-31 has been investigated across several areas of experimental science.

1. Mitochondrial membrane research

Researchers use SS-31 as a model compound for studying interactions involving mitochondrial membranes and cardiolipin.

2. Cardiolipin research

SS-31 has been investigated in cardiolipin-containing membrane systems and mitochondrial preparations.

3. Mitochondrial protein research

Mass-spectrometry-based investigations have examined SS-31 interactions with mitochondrial proteins associated with cardiolipin and oxidative phosphorylation.

4. Membrane biophysics

SS-31 has been used in experimental studies examining lipid packing, membrane surface charge, and peptide-membrane interactions.

5. Experimental mitochondrial disease models

Preclinical studies have examined SS-31 in experimental models of mitochondrial dysfunction, including Barth syndrome models.

These studies represent different experimental systems. Findings from biochemical experiments, animal models, and human clinical research should not be treated as interchangeable evidence.

SS-31 Peptide vs. Elamipretide

For researchers searching scientific databases, the names SS-31 and elamipretide are particularly important.

Elamipretide is commonly identified as SS-31 or MTP-131 in scientific literature. A current PubChem record lists SS-31 and MTP-131 among the compound’s synonyms.

However, terminology can become confusing because the same molecular entity can appear in:

Academic publications
Chemical databases
Research catalogs
Analytical standards
Clinical-trial literature
Pharmaceutical regulatory documents

Using multiple identifiers when searching literature can improve research discoverability.

Recommended search combinations include:

SS-31 peptide + elamipretide

SS-31 + MTP-131

SS-31 + cardiolipin

elamipretide + mitochondrial membrane

SS-31 + mitochondrial bioenergetics

SS-31 Regulatory Context in the United States

An important update for U.S.-focused SEO content is that elamipretide is no longer accurately described simply as an unapproved molecule.

On September 19, 2025, the FDA granted accelerated approval to FORZINITY (elamipretide) for improving muscle strength in adults and pediatric patients with Barth syndrome weighing at least 30 kg.

FDA’s Drug Trials Snapshot identifies FORZINITY as a mitochondrial cardiolipin binder and specifies the approved indication.

For a research-peptide website, this distinction is essential:

SS-31 peptide research material ≠ automatically the FDA-approved FORZINITY pharmaceutical product.

A research supplier should not imply that a research vial is the approved pharmaceutical formulation or that its material is authorized for clinical use.

How to Evaluate SS-31 Research Material

When comparing SS-31 peptide research materials, technical documentation can be more useful than product-page claims alone.

Identity

Look for a clearly defined SS-31/elamipretide identity.

Molecular information

Check the stated molecular formula and expected molecular weight.

Purity documentation

Look for a batch-specific purity result.

HPLC

Review the chromatographic profile when available.

Mass spectrometry

Check whether LC-MS or another mass-spectrometry method confirms molecular identity.

COA

Verify that the Certificate of Analysis corresponds to the actual lot.

Traceability

Ensure that lot, batch, and analytical documentation are internally consistent.

Research-use designation

The material should be appropriately labeled for its intended scientific purpose.

This type of documentation creates a more transparent foundation for laboratory procurement and analytical planning.

SS-31 Peptide Quality Checklist

Before evaluating an SS-31 research material, researchers can ask:

Is the compound clearly identified?
Is the molecular formula provided?
Is the expected molecular weight documented?
Is the chemical form specified?
Is purity supported by analytical testing?
Is an HPLC chromatogram available?
Is mass-spectrometry information available?
Does the COA identify the batch?
Does the lot number match the supplied material?
Is the intended research use clearly stated?

These questions can help distinguish documented analytical information from unsupported marketing language.