What is SS-31? Mitochondrial tetrapeptide

Research-use notice: This article is laboratory and educational information only. It is not medical or legal advice, and it does not include how-to-use instructions. BlueNex Labs materials are research use only and are not intended for human or veterinary use. Research-use-only labelling is not a Health Canada authorization.

Publication status: Prepared for the BlueNex Labs Research Knowledge Centre. Literature and library notes checked September 25, 2026. Primary papers and the public COA library can change; verify the lot report in hand before an assay.

SS-31, on this catalogue, is the synthetic tetrapeptide also discussed as elamipretide and as a Szeto–Schiller peptide. The sequence this site uses is D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2,6-dimethyltyrosine. Four residues, a D-arginine, a dimethyltyrosine, and a C-terminal amide are the identity marks. The 10 mg fill is SS-31 10 mg. The 50 mg fill is SS-31 50 mg. This page is the structure note. It is not a protocol.

A designed tetrapeptide, not a mitochondrial open reading frame

Zhao and colleagues described the cell-permeable peptide D-Arg-Dmt-Lys-Phe-NH2 in the Journal of Biological Chemistry in 2004 (PMID 15178689). The chain is not produced by mitochondrial translation. Two of the four residues are outside the usual ribosomal set: a D-arginine and a dimethyltyrosine. Later papers discuss association with cardiolipin in the inner mitochondrial membrane. That membrane sentence is a target-class description. It is not a lot specification, and it is not a second name for MOTS-c.

MOTS-c is the 16-residue peptide Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg reported by Lee and colleagues from a short open reading frame in mitochondrial 12S rRNA (PMID 25738459). Sixteen residues versus four is the first check. For the catalogue comparison, see MOTS-c versus SS-31. For the class note, see mitochondrial peptides. For the glossary lines, see SS-31 and mitochondrial peptide. For the longer MOTS-c guide, see What is MOTS-c? and the 16-residue laboratory note is MOTS-c.

What the inner-membrane papers are measuring

The 2004 paper and the reviews that followed it place the tetrapeptide in mitochondrial preparations and in cell systems where inner-membrane lipids, including cardiolipin, are part of the model. Endpoints in that literature include membrane association and electron-transport readouts in the system the authors actually ran. Those endpoints stay in the paper. BlueNex Labs does not restate them as a property of a lyophilized cake, and this note does not copy concentrations from the methods section into a purchasing form.

A correct mass for this tetrapeptide has to include dimethyltyrosine and the D-residue, plus the amide if the report's species is the amide. Comparing an SS-31 spectrum with the MOTS-c formula will fail for chemical reasons. Epithalon is a different tetrapeptide, Ala-Glu-Asp-Gly, with its own note at What is Epithalon? and its own vial at Epithalon 10 mg. Four residues are not a shared identity. NAD+ is a redox cofactor, not this peptide. AICAR is a nucleoside. The mitochondrial category hub lists them together because energy-metabolism orders often do. Taxonomy is not a shared certificate.

Two fills, and the published 10 mg library row

The 10 mg listing and the 50 mg listing are separate products. The published report covers the 10 mg sample, batch PIQP, on the SS-31 10 mg certificate. That file does not document the 50 mg vial, and the 50 mg product has no library row yet. It is not permission to attach the MOTS-c PDF, and it is not permission to attach an epithalon report. How to read a peptide COA still governs the published file: sample name, area percent, and mass against D-Arg-Dmt-Lys-Phe-NH2. Purity versus identity is the short version of that split. The 50 mg fill stays a blank cell until its own report is added.

Salt form, if a future PDF names acetate or trifluoroacetate, is a third line. This catalogue does not publish a house factor that converts a salt weight into a free-peptide figure. If the report is silent, leave the salt line blank. For the glossary entries, see acetate salt and TFA salt.

Receiving the dry solid in Canada

The solid is lyophilized because residual water can cleave peptide bonds. Open the parcel the day it arrives. Do not leave it in a vehicle, an outdoor box, or on a loading dock. Move the closed vial into controlled storage and follow the temperature on the product note. A cake that looks different after a cold Canada Post parcel is not an identity test. Do not heat a very cold vial. For the receiving note, see peptide storage for Canadian laboratories. This page does not list a solvent volume.

Paid orders ship on Canada Post Xpresspost inside Canada after Interac e-Transfer. The desk is 4309 Canada Way, Burnaby, BC V5G 1J3. The label sender is a Port Moody, BC PO Box. Put the order number in the Interac message field. For the procurement note, see Canada laboratory procurement. A research-use-only container is not a clinical-trial drug product and it does not carry a Drug Identification Number. For the legal frame, see Are research peptides legal in Canada?.

What the study file should name

Write SS-31, the shop slug, the milligrams, the cap if one is printed, the lot, the observed mass, and whether a report was published. "Mitochondrial peptide" alone fails that line. "Elamipretide" on a secondary blog does not choose between the 10 mg fill and the 50 mg fill. If the purchasing request names only the membrane, send it back for a slug. Sold-out status on either fill is inventory. It does not change the sequence, and it does not create a backorder.

Publishing rules for the lot file are on documentation standards. The scientific lead record is Alice Kay, Ph.D. Those pages explain who hosts the library. They do not replace the mass on the PDF.

What the 50 mg cell still means on receipt

The published 10 mg file is not a document for the 50 mg fill, and it is not a MOTS-c document. Write the date you checked the library, the shop slug, and the milligrams. If a 50 mg report appears later, add the URL on a new line rather than editing the 10 mg file into that result. The 16-residue mass and the tetrapeptide mass should never share a cell. Epithalon's four residues are a third mass. NAD+ has no peptide mass to compare. Keep those rows in the same parcel log only as neighbours, each with its own sample name.

Frequently asked questions

Is SS-31 a shorter form of MOTS-c?

No. SS-31 is the synthetic tetrapeptide D-Arg-Dmt-Lys-Phe-NH2. MOTS-c is a 16-residue peptide encoded by a mitochondrial open reading frame. The masses are not interchangeable.

Does a 10 mg SS-31 report document the 50 mg fill?

No. The 10 mg shop URL is SS-31 10 mg. The published report at the SS-31 10 mg certificate row names that sample. It does not document the 50 mg fill at SS-31 50 mg.

Where is the SS-31 shop URL?

The 10 mg fill is SS-31 10 mg. The 50 mg fill is SS-31 50 mg. This article is the structure note. Price and stock stay on each listing.

What does research use only mean for this tetrapeptide?

The lyophilized solid is sold for laboratory work. The label is not a Drug Identification Number, and this page does not give personal-use steps.

Catalogue cross-reference

For the buy-intent URLs, see SS-31 10 mg and SS-31 50 mg. The published report covers the 10 mg sample; see the SS-31 10 mg certificate. It does not document the 50 mg fill, and it is not a MOTS-c or epithalon report. For the comparison, see MOTS-c versus SS-31.

Orders ship inside Canada only after Interac e-Transfer checkout. Sold-out SKUs remain listed and cannot be added to the cart. Match each vial to its own Certificate of Analysis when a lot is published. Research use only. Not for human or veterinary use. This page is not a protocol.