SS-31 Research Peptide FAQ for Scientists: Common Laboratory Questions Answered

Aubrey Walker

April 21, 2026

ss-31FAQresearch peptidesmitochondria

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.

This comprehensive FAQ covers the most common questions scientists have about SS-31 research peptide in laboratory settings. Researchers can order SS-31 research peptide from Palmetto Peptides with full lot-specific COA documentation. See also: MOTS-C research and mitochondrial function research.

Mechanism and Science

What is SS-31?

SS-31 is a synthetic tetrapeptide research compound with the sequence D-Arg-Dmt-Lys-Phe-NH2 (where Dmt is 2',6'-dimethyltyrosine). It belongs to the Szeto-Schiller peptide family and is studied for its mitochondria-targeting and cardiolipin-binding properties. Also known as elamipretide or MTP-131.

How does SS-31 reach mitochondria in cell-based models?

SS-31 carries net charge approximately +3 at physiological pH. The large negative membrane potential of the inner mitochondrial membrane (approximately -180 mV) creates an electrostatic driving force that concentrates cationic compounds inside mitochondria. This mechanism does not require a specific receptor or active transport process.

What is the molecular weight of SS-31?

Approximately 639.80 g/mol. Molecular formula C32H49N9O5. Monoisotopic mass approximately 639.37 g/mol.

What is cardiolipin and why does it matter for SS-31 research?

Cardiolipin is a unique dimeric phospholipid found almost exclusively in the inner mitochondrial membrane. It carries net charge -2 and plays critical structural roles in supporting electron transport chain complexes and cristae architecture. SS-31 cationic and aromatic residues allow cardiolipin binding in laboratory membrane models.

How does SS-31 differ from MitoQ or SkQ1?

MitoQ and SkQ1 use a triphenylphosphonium (TPP)-conjugated antioxidant scaffold without defined cardiolipin binding. SS-31 uses a peptide-based aromatic-cationic scaffold with specific cardiolipin interaction — making them complementary but mechanistically distinct research tools.

Purity and Quality

What purity grade is appropriate for in vitro mitochondrial assays?

At least 95% HPLC purity for standard cell-based assays. 98% or above recommended for quantitative binding studies, dose-response experiments, or publication-quality research.

What is the difference between SS-31 and elamipretide?

They are the same compound. SS-31 is the original research designation; elamipretide (MTP-131) is the International Nonproprietary Name (INN) assigned for clinical use. The compound is identical.

Reconstitution, Storage, and Handling

How should SS-31 be reconstituted?

Reconstitute lyophilized SS-31 in sterile ultrapure water or sterile PBS (pH 7.4) at your desired stock concentration (typically 1-10 mM). Allow vial to reach room temperature before opening. Mix by gentle pipetting. Filter through 0.22 um sterile membrane for cell culture use.

What are the recommended storage conditions?

Lyophilized SS-31 at -20C or -80C desiccated dark. Reconstituted stocks aliquoted into single-use volumes at -80C protected from light. Maximum 3 freeze-thaw cycles. Working solutions used same-day.

Why is SS-31 stored protected from light?

The Dmt residue contains a phenolic aromatic ring susceptible to photo-oxidation. Both lyophilized powder and reconstituted solutions should be in amber tubes or foil-wrapped containers.

Assay Design

What concentration of SS-31 should I use?

Published studies use 1 nM to 10 uM; most cell-based assays use 100 nM to 1 uM. Always run a dose-response experiment for your specific cell type and assay system.

Does serum in cell culture medium affect SS-31?

Serum albumin can bind cationic peptides, potentially reducing free SS-31 concentration. Some researchers use serum-free conditions during treatment windows to minimize this. Whether this matters depends on concentration used and sensitivity of your endpoint.

For additional research context: NAD+ research, longevity peptide research, cellular health research, BPC-157 and TB-500 research. Order SS-31 research peptide here.