N-Acetyl Selank Amidate

NA Selank Amidate is the most metabolically stable form of Selank, a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) developed at the Institute of Molecular Genetics of the Russian Academy of Sciences from the tuftsin immunomodulatory tetrapeptide. NA Selank Amidate incorporates N-terminal acetylation (Ac-) and C-terminal amidation (-NH2), providing comprehensive exopeptidase protection against both aminopeptidase attack at Thr1 and carboxypeptidase attack at Pro7.

Selank was designed by appending the Pro-Gly-Pro stability extension to the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Tuftsin, first described by Najjar and Nishioka (1970), is an endogenous tetrapeptide cleaved from immunoglobulin G that stimulates phagocytosis and immunological activity through a specific tuftsin receptor on macrophages and neutrophils. The Pro-Gly-Pro extension independently provides C-terminal carboxypeptidase resistance (terminal proline is a poor carboxypeptidase A substrate) and is itself bioactive as a leukocyte chemotactic factor and ECM-derived signalling peptide.

Standard Selank's stability limitations: the N-terminal Thr1 is the primary vulnerability — aminopeptidases attack free alpha-amines, progressively shortening the peptide from the N-terminus. N-terminal acetylation in NA Selank Amidate neutralises this amine, blocking aminopeptidase catalysis comprehensively. C-terminal amidation replaces the free Pro7 carboxylic acid with a carboxamide, eliminating the carboxylate anion required for carboxypeptidase zinc coordination. Together, these modifications extend the compound's half-life in plasma and cell culture media, maintaining more stable effective concentrations throughout long-duration assay periods.

The stability improvement is research-significant in assays lasting beyond 6 hours: gene expression studies (BDNF, TrkB, dopamine receptor mRNA changes by RT-PCR typically require 12-24 hour incubation), protein expression changes (Western blot for BDNF protein requires 24-48 hours), and cell proliferation studies (48-72 hours). For these extended-duration experiments, NA Selank Amidate maintains more consistent receptor exposure than standard Selank, improving dose-response reproducibility.

Selank's published research profile spans GABAergic signalling modulation (GABA-A receptor interaction), enkephalin system amplification through inhibition of enkephalin-degrading enzymes (neprilysin, aminopeptidase M — extending endogenous opioid peptide half-lives), immunomodulatory effects (IL-6 and interferon-gamma regulation in lymphocyte cultures), and BDNF expression changes in hippocampal cell models. NA Selank Amidate enables all these research directions with improved pharmacokinetic stability.

The Signal Labs Selank series — Standard Selank (free termini), Selank Amidate (C-amide only), and NA Selank Amidate (both termini protected) — enables systematic stability-activity relationship research. Running all three in the same assay at matched nominal concentrations quantifies the individual contributions of N-terminal versus C-terminal protection to pharmacodynamic parameters — direct experimental evidence of how terminal modifications affect research compound effectiveness.

Stability comparison experimental design: to quantify NA Selank Amidate's stability advantage over standard Selank, prepare both compounds at 1uM in complete cell culture medium (DMEM + 10% FBS) at 37°C. At 0, 2, 4, 8, and 24 hours, remove aliquots and analyse intact peptide concentration by LC-MS/MS (MRM transitions specific to each compound's sequence). Plot intact concentration versus time; the ratio of remaining intact compound at each timepoint directly quantifies the stability improvement. For GABAergic research: use whole-cell patch-clamp in cultured hippocampal neurons. Apply GABA (10uM) to establish baseline GABA-A current, then co-apply NA Selank Amidate (1nM-1uM) and record current amplitude and decay kinetics changes. Use flumazenil (1uM) as benzodiazepine site control. MW: approximately 907 g/mol. Reconstitute in bacteriostatic water at 1mg/mL. Store lyophilised at -20°C. For laboratory and analytical research purposes only.