N-Acetyl Selank Research, Specifications & Scientific Information

Introduction

N-Acetyl Selank is the heptapeptide Selank with an acetyl group on its N-terminal threonine amine. It is a real and separately registered chemical substance: PubChem carries it as compound identifier 133082488, and the FDA/NCATS substance registration system carries the code J3PM702O93 against it.

It has no research literature. That is the finding of this page, and it is stated at the top rather than buried, because the material is widely offered and widely discussed as though the parent peptide's three decades of Russian clinical and preclinical work belonged to it. Searches of PubMed under every name the molecule travels by return no primary research report on the acetylated peptide, and no study of it is registered on ClinicalTrials.gov.

A page that responded to that by reprinting the Selank record under this heading would be describing one molecule and citing another. So this page sets out what the substance is, what is known about the modification as chemistry, what the parent literature actually covers, and why the gap between the two matters.

What Is N-Acetyl Selank?

Selank is a synthetic heptapeptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its first four residues are tuftsin, a tetrapeptide fragment of the immunoglobulin G heavy chain; the remaining three are the Pro-Gly-Pro extension that the same Moscow group added to several of its regulatory peptides ^[1]. N-Acetyl Selank is that sequence with the N-terminal amine capped by an acetyl group.

Two structures circulate under closely related names, and the difference is worth keeping straight:

• N-Acetyl Selank — acetylated N-terminus, free C-terminal proline carboxylic acid. This is the structure PubChem holds under compound identifier 133082488, molecular formula C35H59N11O10, average mass 793.9 g/mol.
• N-Acetyl Selank Amidate — the same peptide additionally carrying a C-terminal carboxamide. PubChem returns no compound identifier for that name, so no register-sourced formula or mass for it is published on this page.

Neither is an approved medicine. Selank itself is registered as a pharmaceutical product in the Russian Federation; that registration is for the unmodified heptapeptide. Neither the parent nor any acetylated form has been approved by the U.S. Food and Drug Administration for any indication.

N-Acetyl Selank Specifications

The formula and mass above are PubChem's record for compound identifier 133082488, which carries the acetyl group on the N-terminal threonine amine and leaves the C-terminal proline as a free carboxylic acid. That record also carries the FDA/NCATS substance code J3PM702O93. No CAS registry number is recorded against it. Material is also marketed as N-Acetyl Selank Amidate, a doubly modified peptide with a C-terminal carboxamide; queries to PubChem's PUG REST service under that name return no compound identifier, so no formula, mass or registry number is published here for the amidated structure. The two molecules differ by one dalton, which is resolvable analytically and is not resolvable from a product name.

Values that a public register does not carry are shown as not publicly characterised rather than estimated. Identifiers are reference values; the certificate of analysis supplied with a laboratory order is the record for a given lot.

How Does N-Acetyl Selank Work?

Nothing is established, and — unusually even for this library — nothing has been attempted in print.

The parent peptide's own mechanism is only partly resolved. No high-affinity receptor for Selank has been identified. Two molecular interactions have been characterised: inhibition of the plasma enzymes that degrade enkephalins, proposed in 2001 as a route to its anxiolytic activity ^[2], and positive allosteric modulation of GABA binding to brain-cell plasma membrane preparations, reported by radioligand analysis in 2018 ^[1]. Both were measured with the unmodified heptapeptide.

Whether the acetylated analogue reproduces either has not been tested in any published study. The rationale usually given for the modification is pharmacokinetic rather than pharmacodynamic: a capped alpha-amino group is not a substrate for aminopeptidases, so acetylation is a standard route to slowing the degradation of a short peptide. That is a reasonable design premise. It is not a result.

N-Acetyl Selank Mechanism of Action

In vitro research

There is no in vitro study of this molecule. What follows is the nearest published evidence on the question the molecule raises, and it concerns a different peptide.

The Semax precedent. Semax is the other Pro-Gly-Pro-extended heptapeptide from the same research programme, and its N-terminally acetylated form has been characterised. Acetylation removed the free amine that anchors copper(II) to the parent peptide, changing the principal complex at physiological pH from a four-nitrogen coordination sphere to a distorted three-nitrogen-one-oxygen sphere, shifting its formal redox potential, and reversing its behaviour toward ascorbate. In SH-SY5Y neuroblastoma cells the acetylated peptide did not protect against copper(II)-induced toxicity, while the unmodified peptide did — which the authors read as evidence for the crucial role of the free N-terminus in that protection ^[3].

Two things follow, and only two. First, N-terminal acetylation of a peptide in this family is capable of abolishing an activity the parent had, in the same assay, in the same laboratory. Second, that was demonstrated for Semax and not for Selank, whose N-terminal residue is threonine rather than methionine and whose reported interactions are with enzymes and membrane receptors rather than with metal ions. The Semax result is a caution about assuming equivalence; it is not a prediction about this compound.

Findings in this section were obtained with a different peptide, in solution chemistry and in a cultured cell line. Nothing in them establishes anything about N-Acetyl Selank, about intact animals, or about humans.

What Is N-Acetyl Selank Being Researched For?

Nothing, in the sense the question is usually asked. No indexed publication reports research with this molecule, and no clinical trial of it is registered.

The research topics commonly listed under the name belong to the unmodified parent, where they are the subject of an active if geographically concentrated literature — anxiolytic activity, enkephalin-degrading enzyme inhibition, GABAergic gene expression, brain-derived neurotrophic factor expression in the rat hippocampus, and behavioural work in rodent stress models. Those are set out, with their sources and their limitations, on the Selank entry. They are not restated here, because restating them under this heading would attach them to a substance that was not used to generate them.

What can be said about this compound specifically is confined to chemistry: it is the acetylated form of a known sequence, it has its own PubChem and substance-registry records, and the modification belongs to a class of changes made to slow enzymatic degradation.

Current Research Status

Status as of September 22, 2026. This block is rendered from maintained fields, not from prose, so it cannot go stale in one place and stay current in another.

N-Acetyl Selank vs Related Compounds

The parent peptide

Selank is the unmodified heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro, registered as a pharmaceutical product in the Russian Federation and supported by a body of Russian preclinical and clinical reports ^{[2, 1]}. Every one of those reports was generated with the unmodified molecule.

The other acetylated variant

N-Acetyl Semax stands in exactly the same relation to Semax, with one difference: two indexed chemistry papers exist on the acetylated Semax molecule ^[3], and none exists on the acetylated Selank molecule. Between the two acetylated variants, this is the thinner record.

The amidated form

Material sold as N-Acetyl Selank Amidate carries a further C-terminal modification and has no PubChem record under that name. Treating it, the acetylated acid, and the unmodified parent as one compound collapses three distinct substances into a single set of claims.

Tuftsin itself

The parent's first four residues are tuftsin, a natural immunoglobulin fragment with a literature of its own going back to the 1970s. That literature is not evidence about Selank, and it is two removes from being evidence about the acetylated analogue.

No comparison of effect between these compounds is made on this page.

Chemical & Molecular Characteristics

The backbone is seven residues: threonine, lysine, proline, arginine, proline, glycine, proline. Three prolines and a guanidinium-bearing arginine make it a highly polar, strongly basic peptide, and acetylation changes that balance in a specific way.

Acetylation removes a positive charge. The unmodified peptide carries three basic centres at physiological pH — the N-terminal alpha-amine, the lysine side-chain amine, and the arginine guanidinium. Capping the alpha-amine removes one of them. The molecule stays strongly cationic, but its net charge, isoelectric point and ion-exchange behaviour all shift, which matters for any purification or analytical method that separates on charge.

It is the point of the modification. Aminopeptidases require a free alpha-amino group. Acetylation is the standard way to remove that requirement from a short peptide, and it is why the modification is made. Whether it measurably extends this sequence's survival has not been published; for the acetylated Semax molecule the corresponding question was at least asked in print.

The threonine hydroxyl is an additional handle. A side-chain hydroxyl adjacent to the modified terminus can participate in acyl migration under some conditions, producing an O-acetylated isomer identical in mass to the intended N-acetylated product. Mass spectrometry cannot distinguish the two; nuclear magnetic resonance or a chromatographic method validated against an authentic standard can.

Three prolines constrain the backbone. Proline-rich sequences populate multiple slowly interconverting cis/trans amide isomers, which can present as peak broadening or as multiple partially resolved peaks in reversed-phase chromatography. A purity figure derived from peak-area integration is sensitive to how that behaviour was handled by the method.

Recorded identifiers are PubChem compound identifier 133082488, FDA/NCATS substance code J3PM702O93, molecular formula C35H59N11O10 and average mass 793.9 g/mol. No CAS registry number resolves for the substance, so that field is published as unknown rather than filled with the parent peptide's number, which belongs to a different molecule.

Frequently Asked Questions

Scientific References

1. Vyunova TV, Andreeva L, Shevchenko K, et al.. Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity Protein and peptide letters; 2018. PMID 30255741 doi:10.2174/0929866525666180925144642
2. Zozulya AA, Kost NV, Yu Sokolov O, et al.. The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity Bulletin of experimental biology and medicine; 2001. PMID 11550013
3. Magrì A, Tabbì G, Giuffrida A, et al.. Influence of the N-terminus acetylation of Semax, a synthetic analog of ACTH(4-10), on copper(II) and zinc(II) coordination and biological properties Journal of inorganic biochemistry; 2016. PMID 27586814 doi:10.1016/j.jinorgbio.2016.08.013

Every identifier above is resolved against PubMed, Crossref or ClinicalTrials.gov at build time, and the title returned by the register is compared with the title stored here. A page does not publish if a reference fails to resolve.

Research-Use Information

For in vitro research use only. This material is a laboratory reagent. It is not a drug, food, dietary supplement, or cosmetic and is not for human or veterinary use, including ingestion, injection, or any other administration. No information on this page describes or implies any effect in humans or animals. Sold only to researchers under our Terms of Sale.