Quick answer: SS-31 is a synthetic tetrapeptide, meaning a chain of just four amino acids, studied in laboratory research on mitochondria. Our SS-31 10mg product is a lyophilized (freeze-dried) powder with the sequence D-Arg-Dmt-Lys-Phe-NH₂, CAS 736992-21-5 and a molecular weight of about 639.8 g/mol. This SS-31 peptide profile covers what each part of the molecule is and how the vial is verified.
What is SS-31, and why does it have so many names?
SS-31 is also written SS31, and it is known as MTP-131 and as the Szeto-Schiller peptide. The last name points to the researchers who first described this family of cell-permeable, mitochondria-targeting peptides. Mitochondria are the structures inside cells that handle most energy production.
Published laboratory research has used SS-31 to examine mitochondrial bioenergetics, oxidative stress and cellular energy dynamics. Much of that work is in cell and preclinical models. For the mechanism in more depth, see our article SS-31: The Peptide Targeting the Powerhouse of the Cell.
SS-31 peptide profile: the identifiers at a glance
These are the figures listed on the product page for SS-31 | 10mg.
| Item | Detail |
|---|---|
| Sequence | D-Arg-Dmt-Lys-Phe-NH₂ |
| Length | 4 amino acids |
| CAS number | 736992-21-5 |
| Molecular formula | C₃₂H₄₉N₉O₅ |
| Molecular weight | ~639.8 g/mol |
| Form | Lyophilized powder |
| Vial size | 10mg |
What does the sequence D-Arg-Dmt-Lys-Phe-NH₂ mean?
Each part of the name describes a deliberate design choice.
- D-Arg: arginine in its mirror-image "D" form. Most natural peptides use the "L" form, so this is an unusual feature.
- Dmt: 2′,6′-dimethyltyrosine, a modified version of tyrosine with two extra methyl groups. It is not one of the 20 standard amino acids.
- Lys: lysine. With arginine, it gives the peptide two positively charged (cationic) residues.
- Phe-NH₂: phenylalanine, with the end of the chain capped as an amide.
The product page describes this mix of cationic and aromatic residues as the basis for cell entry and for localizing at the inner mitochondrial membrane. It also describes a strong affinity for cardiolipin, a phospholipid that helps organize the electron transport chain. These are the properties researchers propose, drawn from laboratory studies.
What is in the vial and how does it ship?
The vial holds SS-31 as a freeze-dried powder. The product page lists the peptide as the product and does not list added ingredients. Our peptides are synthesized at a WHO/GMP and ISO 9001 certified laboratory in California.
The product page does not give a storage temperature. Follow the instructions on the vial label and keep the unopened vial sealed. Dry powder is generally more stable than dissolved peptide, which is why it ships this way. Our guide to lyophilization explains why.
How is SS-31 verified?
Three checks matter: identity by mass spectrometry, purity by HPLC, and the peptide content of the vial. Our line-by-line COA guide covers each line, so here we focus on what is specific to SS-31.
The Certificate of Analysis shown above should be read with the sequence in mind.
- Mass: the main signal should sit near the expected molecular weight of about 639.8 g/mol. Singly charged ions appear near 640.4 m/z.
- Dmt substitution: if ordinary tyrosine were used by mistake, the mass would come out about 28 units lower. Mass testing catches this.
- D versus L arginine: a swap changes the shape but not the mass. A single mass reading cannot rule it out, so synthesis control and the chromatogram matter.
- Purity and content: HPLC purity is a percentage of the peptide signal. It is not the same as how much peptide is in the vial.
Frequently asked questions
What is cardiolipin?
Cardiolipin is a phospholipid found mainly in the inner mitochondrial membrane. Researchers study SS-31 partly because of its reported affinity for it.
Is SS31 the same compound as SS-31?
Yes. SS31 is simply a spelling variant with no hyphen, and the compound is the same.
How many amino acids does SS-31 have?
It has four, one of which is a modified, non-standard residue. That makes it much smaller than most research peptides.
Does the SS-31 vial contain anything besides the peptide?
The product page describes a high-purity lyophilized peptide powder and lists no other ingredients.
Where is SS-31 made?
It is synthesized at a WHO/GMP and ISO 9001 certified laboratory in California. BioPure does not own that facility.
Every lot we sell has a Certificate of Analysis you can read before you order. Questions before you buy? Our team is in Chandler, Arizona: (888) 745-1505 or our contact page.
View SS-31 | 10mgAll products sold by BioPure Peptides are intended strictly for in-vitro laboratory and research use only. They are not for human or animal consumption. These statements have not been evaluated by the U.S. Food and Drug Administration, and these products are not intended to diagnose, treat, cure, or prevent any disease.