Selank (Tuftsin Analogue)
Selank CAS Number and Chemical Identity
Selank carries CAS Registry Number 129954-34-3, PubChem CID 11765600 and UNII TS9JR8EP1G, with molecular formula C33H57N11O9 and molecular weight 751.9 Da. It also appears under the development code TP-7, which is worth knowing when searching older literature.
Key facts
- CAS Registry Number
- 129954-34-3
- PubChem CID
- 11765600
- UNII
- TS9JR8EP1G
- Development code
- TP-7
- Molecular formula
- C33H57N11O9
- Molecular weight
- 751.9 Da
- Common salt form
- Acetate or trifluoroacetate
Why identifiers matter more than names
Selank appears as Selank, Selanc, TP-7, TKPRPGP, and under its full systematic name. Older Russian-language literature frequently uses the development code. A CAS number, PubChem CID and UNII are unambiguous where those labels are not, and comparing identifiers rather than names is the only reliable way to check that a certificate of analysis describes the compound a paper studied.
The salt form and gross weight
Synthetic peptides purified by reverse-phase HPLC are typically isolated as trifluoroacetate or acetate salts. The counter-ion contributes to the total weight of powder in the vial, so net peptide content is lower than gross weight. A certificate that reports the two separately is describing this correctly; one that reports only a gross figure is not telling you how much peptide you have.
Research material referenced
Selank 10mg — third-party HPLC tested
Confirming identity
Mass spectrometry against the theoretical mass for TKPRPGP is the identity check. Selank has no methionine, so the +16 Da oxidation satellite that appears on many peptide spectra should not be present — if it is, something other than simple methionine oxidation is going on and warrants explanation.
Confirming purity
Reverse-phase HPLC quantifies how much of the sample is the target peptide against truncated sequences, deletion sequences and synthesis by-products. Seven residues is a short synthesis with few opportunities for truncation, so purity figures are typically high and an unexpectedly low one deserves scrutiny. As always, a purity number with no chromatogram behind it is an assertion rather than a measurement.
Extended research context
The Selank (Tuftsin Analogue) deep dive
Deep dive: preserving a signal rather than supplying one
Selank's most specifically characterised activity is not receptor binding. Work published in the Bulletin of Experimental Biology and Medicine in 2001 and 2002 reported that it inhibits enkephalin-degrading enzymes, measured directly on plasma enkephalinase activity, thereby extending the half-life of endogenous enkephalins rather than acting at opioid receptors itself. That distinction is routinely muddled and it matters: an agonist activates the receptor wherever the drug reaches, at whatever concentration is given, while a degradation inhibitor only lets the ligand the body is already releasing persist longer. The effect is bounded by endogenous release and occurs only where that release happens. The same logic underlies DPP-4 inhibitors in the incretin field, which prolong native GLP-1 rather than supplying an analogue - and instructively, that class produces much smaller effects than the receptor agonists do.
Deep dive: what the sequence does and does not contain
TKPRPGP is unusual among research peptides for what is absent from it. There is no cysteine, so no disulfide bonds form or scramble and no reducing agent is needed. There is no methionine, so the thioether oxidation that adds 16 Da and dominates handling guidance for MOTS-c and Semax does not apply. There is no asparagine or glutamine either, ruling out deamidation. What remains is straightforward hydrolysis, and three prolines in seven residues resist even enzymatic cleavage well, because proline locks the backbone rotation peptidases require. One practical cost of that composition: no aromatic residues means almost no absorbance at 280 nm, so the standard spectrophotometric quantification method does not work on it.
Deep dive: reading a two-literature evidence base
PubMed indexes roughly 135 Selank records against about 690 for its parent peptide tuftsin - an inversion worth noticing, since most designed analogues eventually outgrow the parent they replaced. Most of the tuftsin literature is immunological and predates Selank entirely, so it is not evidence about Selank. Within Selank's own record the split is the same one Semax shows: mechanistic work in internationally indexed journals, assessable directly; clinical work concentrated in Russian-language publications, indexed by translated title and often without accessible English full text. That is evidence which is hard to verify independently, which is not the same as evidence that is absent, and not the same as evidence that is established.
Research applications
- ▸Enkephalin and enkephalinase pathway research
- ▸GABAergic receptor expression studies in rodent models
- ▸BDNF expression research, including intranasal administration routes
- ▸Comparative work on proline-stabilised peptide design
- ▸Tuftsin and immunopeptide structure-activity research
Handling checklist
- ✓Store lyophilised material cold, dry and protected from light
- ✓No reducing agent needed — the sequence contains no cysteine
- ✓No methionine oxidation to expect; a +16 Da satellite warrants explanation
- ✓Do not rely on 280 nm absorbance — there are no aromatic residues
- ✓Introduce diluent gently against the vial wall; swirl rather than shake
- ✓Aliquot to avoid repeated freeze-thaw cycles
Common research-handling mistakes
Learnt from thousands of researcher orders across our UK labs.
✗ Describing Selank as an opioid or opioid agonist
Fix: Reported work describes inhibition of enkephalin-degrading enzymes, not receptor binding. It preserves endogenous enkephalins rather than supplying an agonist.
✗ Treating the benzodiazepine contrast as a safety claim
Fix: The mechanistic difference is real — expression-level rather than direct allosteric modulation — but it supports no comparative claim about safety or dependence.
✗ Citing tuftsin literature as evidence about Selank
Fix: Tuftsin has roughly five times more papers, most of them immunological and predating Selank. They are different compounds.
✗ Reading a BDNF expression change as a demonstrated outcome
Fix: The work measured expression in rat hippocampus. Expression is upstream of function and upstream again of any clinical claim.
✗ Treating Russian registration as equivalent to MHRA approval
Fix: Authorisations are jurisdictional and do not transfer. Selank has never been assessed by the MHRA, EMA or FDA.
Continue researching
Peer-reviewed guides, comparators and matched reference materials.
Related questions researchers ask
- What is Selank?
- What is tuftsin?
- How does Selank affect enkephalins?
- Does Selank work like a benzodiazepine?
- Is Selank approved in the UK?
- How does Selank differ from Semax?
Frequently asked questions
- What is the CAS number for Selank?
- 129954-34-3. PubChem CID 11765600 and UNII TS9JR8EP1G identify the same compound.
- What does TP-7 mean?
- It is Selank's development code, used in some of the older literature. Searching for it can surface papers that do not use the name Selank.
- Why does vial weight not equal peptide content?
- Synthetic peptides are supplied as salts, and the counter-ion contributes to gross weight. Net peptide content should be stated separately.
Primary sources & clinical trials
Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.
- PubChemPubChem · Selank (CID 11765600)pubchem.ncbi.nlm.nih.gov
- PubMedPubMed — Selank literaturepubmed.ncbi.nlm.nih.gov
- PubMedZozulya AA et al., Inhibitory effect of Selank on enkephalin-degrading enzymes — Bull Exp Biol Med 2001 (PMID 11550013)pubmed.ncbi.nlm.nih.gov
- PubMedSokolov OY et al., Selank and plasma enkephalin-degrading enzyme activity — Bull Exp Biol Med 2002 (PMID 12432865)pubmed.ncbi.nlm.nih.gov
- PubMedInozemtseva LS et al., Intranasal Selank regulates BDNF expression — Dokl Biol Sci 2008 (PMID 18841804)pubmed.ncbi.nlm.nih.gov
- PubMedZozulia AA et al., Efficacy and mechanisms of the peptide anxiolytic selank — 2008 (PMID 18454096)pubmed.ncbi.nlm.nih.gov
- PubMedKolik LG et al., Selank, peptide analogue of tuftsin — Bull Exp Biol Med 2019 (PMID 31625062)pubmed.ncbi.nlm.nih.gov
- PubMedFridkin M, Tuftsin: its chemistry, biology, and clinical potential — Crit Rev Biochem Mol Biol 1989 (PMID 2667894)pubmed.ncbi.nlm.nih.gov
- RefMHRA — Medicines and Healthcare products Regulatory Agencygov.uk
- GuidelineGoogle — Creating helpful, reliable, people-first contentdevelopers.google.com
Written and reviewed by
Jack Muncaster · Founder, UK Peptides
Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.
More Selank (Tuftsin Analogue) articles
- Selank Storage, Stability and ReconstitutionSelank has no cysteine and no methionine, so the two usual degradation routes do not apply. What that changes about handling, and what it does not.
- Selank in the Published LiteratureAbout 135 indexed PubMed records, against 690 for its parent peptide tuftsin. How the mechanistic and clinical literatures split, and how to read them.
- Selank Regulatory StatusSelank has a Russian registration history and holds no MHRA, EMA or FDA authorisation. What a national registration means, and what it does not transfer.
- What Is Selank? A Complete Research OverviewSelank is a synthetic heptapeptide built from tuftsin with a Pro-Gly-Pro extension. Structure, enkephalin mechanism, regulatory status and the evidence base.
- What Is Tuftsin? An Immunopeptide From AntibodyTuftsin is a four-residue peptide released from immunoglobulin G that stimulates phagocytic activity. It is the bioactive core of Selank, and better studied than it.
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