Quick answer: Selank is a synthetic seven-residue peptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) designed as a stabilized analog of tuftsin, a naturally occurring tetrapeptide fragment of immunoglobulin G. It was developed in Russia and is studied in the preclinical literature for neuropeptide, neurotransmitter-related and immune-signaling questions. It is a laboratory research compound only. This explainer covers the name, structure, research themes, how it differs from Semax, and what to check on a certificate of analysis.
Where the name Selank comes from
Selank is a coined name rather than a sequence abbreviation. The compound was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences as part of a program on tuftsin analogs, and the name stuck as a trade-style label. In supplier catalogs you may also see it written as “Selank peptide” or by its sequence, TP-7.
Because the label does not describe the molecule, it helps to know the structure. Selank is a heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its molecular weight is roughly 751 g/mol. The first four residues, Thr-Lys-Pro-Arg, are tuftsin itself. The additional Pro-Gly-Pro tail was added by the designers to slow enzymatic breakdown, since natural tuftsin is cleared very quickly in biological systems.
For the chemistry in more detail, see Selank chemical structure and synthesis.
Tuftsin and why an analog was designed
Tuftsin (Thr-Lys-Pro-Arg) was described in the 1970s as a fragment released from the heavy chain of immunoglobulin G. In early work it was associated with the activity of phagocytic cells, which made it a subject of immune-signaling research. Its practical drawback as a laboratory tool is a very short half-life in biological media.
Adding the proline-glycine-proline extension is a classic stabilization strategy: proline-rich sequences resist many peptidases. That is the core design idea behind Selank, and the same logic appears in the related Russian peptide Semax, which pairs an ACTH fragment with a Pro-Gly-Pro tail.
The background story is told in the discovery and history of Selank.
What the preclinical literature examines
Everything below is preclinical or mechanistic. None of it is a statement about use in people.
Enkephalin-related enzymes. Cell-free and tissue assays have reported that Selank can affect enzymes that degrade enkephalins, the short endogenous opioid-like peptides, and in so doing alter their measured levels in the models used.
Gene expression in rodent brain tissue. Some studies report changes in expression of brain-derived neurotrophic factor (BDNF) and other genes in rat hippocampus after exposure to Selank. Others used broader expression profiling in rodent tissue and described shifts in genes connected to neurotransmitter signaling and immune function.
GABAergic and monoaminergic readouts. Neurochemical studies have looked at whether Selank alters markers related to GABA receptor signaling and serotonin metabolism in animal models.
Immune-signaling markers. Because the parent tuftsin sequence is immune-related, researchers have also measured cytokine expression and interleukin patterns in cell and animal systems.
A caution on interpretation: much of this literature comes from a small number of research groups, and sample sizes and methods vary. Independent replication is limited, so reading the primary papers directly is the right approach. Our mechanism of action article and preclinical research summary organize the primary sources.
Selank, Semax and related peptides at a glance
Selank and Semax are frequently mentioned together because both came out of Russian peptide programs and both end in Pro-Gly-Pro. They are different molecules, though. The table below shows the basic descriptors only.
| Compound | Length | Parent sequence | Typical research context |
|---|---|---|---|
| Selank | 7 residues (TKPRPGP) | Tuftsin (Thr-Lys-Pro-Arg) plus Pro-Gly-Pro | Enkephalin-enzyme, gene expression and immune-signaling models |
| Tuftsin | 4 residues (TKPR) | IgG heavy-chain fragment | Phagocyte and immune-signaling assays; short half-life |
| Semax | 7 residues (Met-Glu-His-Phe-Pro-Gly-Pro) | ACTH(4-7) plus Pro-Gly-Pro | Neurotrophin and neuroactive peptide models |
| KPV | 3 residues (Lys-Pro-Val) | alpha-MSH C-terminus | Cell signaling and epithelial transport models |
Handling the lyophilized powder
Selank is supplied as a freeze-dried powder. General practice for lyophilized peptides applies: keep sealed vials cold, dry and away from light, avoid repeated temperature cycling, and record the date a vial is first opened. Peptides containing arginine and lysine can be hygroscopic, so letting a cold vial reach room temperature before opening it limits condensation on the powder.
Practical notes are in Selank storage and handling.
What to check on a Selank certificate of analysis
A seven-residue peptide with several basic side chains can pick up truncated or deletion sequences during synthesis, so the purification and documentation step matters.
HPLC purity with the chromatogram, not only a percentage. Look at whether minor peaks are visible and how they are integrated. Understanding HPLC purity explains what the numbers mean.
Identity confirmation. As generic buying guidance, ask what method confirms that the molecular weight matches the expected value of about 751 g/mol, and read the report to see it.
Lot reference and date that match the vial, and the name of the testing laboratory.
Stated fill amount and whether it refers to total powder or net peptide.
Walk through each section with how to read a COA and Selank purity testing. For sourcing questions see where to buy Selank, and for our listing see the Selank product page.
Common misunderstandings
“Selank is just tuftsin.” Tuftsin is the first four residues; Selank adds a three-residue tail and behaves differently in stability terms.
“Selank and Semax are the same family member.” They share a stabilizing tail but have different parent sequences. Our Selank vs. Semax comparison sets them side by side.
“Its regulatory status elsewhere applies here.” Any status a peptide has in another country does not change that products sold by V8 Peptides are for laboratory research only.
“Animal data predicts human outcomes.” It does not, and this article makes no such claim.
Frequently asked questions
What is Selank?
A synthetic heptapeptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a more stable analog of the immune-related tetrapeptide tuftsin.
What does the name Selank mean?
It is a coined name, not a sequence code. The sequence itself is written TKPRPGP.
How is Selank different from tuftsin?
Selank contains tuftsin (the first four residues) plus a Pro-Gly-Pro tail added to slow enzymatic breakdown.
How is Selank different from Semax?
Both end in Pro-Gly-Pro, but Semax is built on a fragment of ACTH while Selank is built on tuftsin. They are separate compounds with separate literatures.
What is Selank's molecular weight?
Roughly 751 g/mol.
Is Selank approved in the United States?
No. V8 Peptides sells it for laboratory research use only, not for human or animal consumption.
What kind of studies mention Selank?
Rodent and cell studies on enkephalin-degrading enzymes, gene expression in brain tissue, neurotransmitter-related markers and immune signaling. All preclinical.
Why are some Selank sources hard to verify?
Much of the primary literature comes from a few research groups, so independent replication is limited. Read the original papers rather than summaries.
What should I look for on a Selank COA?
An HPLC chromatogram, an identity method that confirms the expected mass, a lot reference matching your vial, a test date and a named laboratory.
How is lyophilized Selank stored?
Sealed, cold, dry and protected from light, with temperature cycling avoided and the opening date recorded.
References
- Najjar VA, Nishioka K. Tuftsin: a natural phagocytosis stimulating peptide. Nature. 1970;228:672-673.
- Inozemtseva LS, et al. Intranasal administration of the synthetic analogue of ACTH(4-10) Semax and tuftsin analogue Selank influence on BDNF expression in rat hippocampus. Neurochemical Journal. 2008.
- Kolomin T, et al. Heptapeptide Selank affects expression of genes involved in neurotransmission and immune response in rodent brain. PLoS One. 2013.
All V8 Peptides products are sold for laboratory research use only. They are not drugs, foods, or cosmetics and are not intended for human or animal consumption.