01 / Comparison
Semax vs Selank, side by side.
Semax and Selank are both seven-residue chains that end in Pro–Gly–Pro. Their first four residues differ: Semax begins with Met–Glu–His–Phe, the ACTH(4–7) segment, and Selank with Thr–Lys–Pro–Arg, the tuftsin sequence.
| Semax | Selank | |
|---|---|---|
| Sequence, one-letter | MEHFPGP | TKPRPGP |
| Sequence, three-letter | Met–Glu–His–Phe–Pro–Gly–Pro | Thr–Lys–Pro–Arg–Pro–Gly–Pro |
| Length | 7 residues | 7 residues |
| Residues 1–4 | Met–Glu–His–Phe, ACTH(4–7) | Thr–Lys–Pro–Arg, tuftsin |
| Residues 5–7 | Pro–Gly–Pro | Pro–Gly–Pro |
| Formula, free peptide | C37H51N9O10S | C33H57N11O9 |
| Molecular weight, free peptide | 813.9 g/mol | 751.9 g/mol |
| PubChem CID | 9811102 | 11765600 |
- SelankThe tuftsin-based chain with the same Pro–Gly–Pro ending.
02 / Molecular architecture
A closer look at the chain.
Met–Glu–His–Phe corresponds to ACTH residues 4–7. Pro–Gly–Pro completes the chain. Being derived from part of ACTH does not make Semax the full ACTH hormone.
- 7 amino acids
- ACTH(4–7) segment
- Pro–Gly–Pro extension
- 1Met
- 2Glu
- 3His
- 4Phe
- 5Pro
- 6Gly
- 7Pro
Reference information: [1][2][3][4]. Actual lot identity must be verified separately.
What ACTH(4–7) means in this name.
The parenthetical positions identify the Met–Glu–His–Phe segment from the ACTH reference. Pro–Gly–Pro follows it in Semax. These positions describe a relationship to the parent sequence; they are not the total length of Semax, whose reference chain contains seven residues.
Sequence blocks are not blended ingredients.
Breaking MEHFPGP into MEHF and PGP is a way to explain the design. In the reference structure, the residues belong to one linked backbone. That is different from combining two separate fragment materials, even if a component list contained the same residue names.
03 / Read the evidence
Research & analytical context.
The NLM identity record describes the ACTH(4–7)-Pro–Gly–Pro sequence. The two sequence regions form one molecule, rather than a mixture of separate peptide fragments. Molecular identity depends on the complete chain.
Read the references: [1][2][3][4].
The distinction that matters
Semax and Selank share a Pro–Gly–Pro ending but have different preceding residues. That shared ending does not make them the same compound.
04 / From reference to record
Know the lot, too.
A publication describes its own test material. Your lot’s certificate describes what was tested on that lot. Keep the compound name, batch number and reported methods together when reviewing a result.
Identity & composition
Check sequence or chemical form, terminal modifications, counterion and—where relevant—each blend component.
Analytical results
Read purity, content, sterility and endotoxin results as separate measurements. Only call a test passed when the actual report supports it.
Handling & storage notes
Lyophilized material: Store at −20°C; protect from light and moisture.
Follow the material-specific label and supporting storage documentation. These temperatures do not establish a shelf life.
How to store lyophilized peptides05 / Reference questions
A few details, explained.
Does Semax contain the complete ACTH sequence?
No. The reference uses the ACTH(4–7)-related segment followed by Pro–Gly–Pro. The complete ACTH chain is a different molecular identity.
How does Semax differ from Selank?
Both are seven-residue chains ending in Pro–Gly–Pro. Semax begins with Met–Glu–His–Phe and Selank with Thr–Lys–Pro–Arg, so they match at three of seven positions, all in the ending. The comparison is structural, not a claim that the two behave the same way experimentally.
06 / Continue reading
Go to the source.
Each source is labeled by its type. External sources are not Pioneer batch certificates.
- NLM MeSH · Semax / ACTH(4–7)-Pro–Gly–Pro identityPublic record · Read source (opens a new tab)
- PubChem · Semax identity record, CID 9811102Public record · Read source (opens a new tab)
- PubChem · Selank identity record, CID 11765600Public record · Read source (opens a new tab)
- PubChem · Tuftsin identity record, CID 156080Public record · Read source (opens a new tab)