Semax vs Selank: two heptapeptides compared
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Semax and Selank are both synthetic heptapeptides, seven amino acids long, and both end in the same three residues: Pro-Gly-Pro. They differ in their first four residues, which come from different parent sequences. This guide sets the two side by side so each can be identified from its sequence and documentation.
Semax and Selank at a glance
| Semax | Selank | |
|---|---|---|
| CAS number | 80714-61-0 | 129954-34-3 |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Length | 7 amino acids | 7 amino acids |
| First four residues | Met-Glu-His-Phe, from ACTH(4–7) | Thr-Lys-Pro-Arg, the tetrapeptide tuftsin |
| Last three residues | Pro-Gly-Pro | Pro-Gly-Pro |
| Synonyms | None listed | TP-7, Selanc |
What do the two peptides have in common?
Both were designed the same way: a short sequence taken from a naturally occurring peptide, extended at the C-terminus with Pro-Gly-Pro. Both emerged from the same Russian peptide research programme, and both are supplied as a white lyophilised powder.
How do they differ?
The difference is the parent sequence. Semax begins with residues 4 to 7 of ACTH (adrenocorticotropic hormone). Selank begins with tuftsin, a four-residue peptide. Because the first four residues differ, the two have different masses and different CAS numbers, and they are distinct compounds.
One practical note follows from the sequences. Semax contains a methionine residue, which in peptide chemistry is one of the residues most often associated with oxidation. Selank contains none. Storage for both should follow the documentation supplied with the product.
How are Semax and Selank supplied by Ascend Research?
| Listing | Format |
|---|---|
| Semax 10mg | One vial, single compound |
| Selank 10mg | One vial, single compound |
| [2V] Selank + Semax Research Duo | Two separate vials, 10mg each, not premixed |
| [2V] DSIP + Selank Research Duo | Two separate vials: DSIP 15mg and Selank 10mg |
Separate-vial formats are explained in peptide blends vs separate vials.
What should the documentation show?
- The compound name on the certificate matches the vial label exactly. The names are similar, so check carefully.
- The batch number matches.
- An HPLC purity figure and an identity result consistent with the stated sequence.
Batch documents are on the COAs page. See also how to read a peptide certificate of analysis.
Frequently asked questions
What is the difference between Semax and Selank?
Both are seven-residue peptides ending in Pro-Gly-Pro. Semax begins with Met-Glu-His-Phe from ACTH(4-7), while Selank begins with Thr-Lys-Pro-Arg, the tetrapeptide tuftsin.
What is the sequence of Semax?
Met-Glu-His-Phe-Pro-Gly-Pro.
What is the sequence of Selank?
Thr-Lys-Pro-Arg-Pro-Gly-Pro.
What are the CAS numbers for Semax and Selank?
Semax is CAS 80714-61-0 and Selank is CAS 129954-34-3.
Is the Selank + Semax duo a premixed blend?
No. The duo supplies two separate vials of 10mg each.
All Ascend Research products are sold strictly for laboratory research use only. They are not for human or animal use, and nothing in this article is medical advice.
The Ascend Research team
![[2V] DSIP + Selank Research Duo (separate vials)](http://www.ascendpeptides.com.au/cdn/shop/files/IMG-0615.png?v=1781699394&width=533)
