What Is Selank? Structure, Sequence and Relation to Tuftsin

Selank is a synthetic seven-residue peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, with the formula C33H57N11O9, an average molecular weight of about 751.9 Da and the CAS number 129954-34-3. It consists of tuftsin, a naturally occurring tetrapeptide, extended at the C-terminus with the tripeptide Pro-Gly-Pro.

What is tuftsin?

Tuftsin, Thr-Lys-Pro-Arg, is a four-residue fragment of the heavy chain of immunoglobulin G. It was described in the 1970s for its effects on phagocytic cells. On its own it is short-lived in biological fluids, which limits its usefulness as a research tool.

Why add Pro-Gly-Pro?

The Pro-Gly-Pro extension is the same design element used in Semax, a related peptide developed in Russia. Proline-rich sequences resist many peptidases, and the extension is associated with a longer lifetime of the peptide in biological matrices. Selank was developed in Russia, where it is registered as a medicine.

What does the published literature report?

Most published work on Selank comes from Russian research groups and is conducted in rodents. Studies have examined its effects on anxiety-related behavior, on memory impairment models and on brain-derived neurotrophic factor content in rats [1], on behavior during morphine withdrawal in rats [2], and on the expression of genes for chemokines and cytokines [3]. These are animal and cell findings and do not describe any use in humans.

How is Selank identified in the laboratory?

Selank contains two basic residues, lysine and arginine, and no aromatic amino acids. The absence of aromatic residues means it absorbs weakly at 280 nanometers, so HPLC methods detect it near 214 to 220 nanometers, where the peptide bond absorbs. Identity is confirmed by mass spectrometry against the theoretical mass.

Frequently asked questions

How is Selank different from Semax?

Both carry the Pro-Gly-Pro extension, but the core differs: Selank is built on tuftsin (TKPR), Semax on a fragment of adrenocorticotropic hormone (MEHF). They have different sequences, molecular weights and literatures.

Is N-acetyl Selank amidate the same compound?

No. Like the modified forms of Semax, it carries different end groups and a different molecular weight and should be treated as a separate compound.

Does FLASK list Selank?

Yes, as Selank 10 mg, with sequence, formula and CAS number on the product page.