What is Selank?
Selank is recorded under CAS 129954-34-3, formula C33H57N11O9, average molecular weight 751.88, and the seven-residue sequence H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH, filed under the synonym tuftsin analogue TP-7. The first four residues reproduce tuftsin, the fragment released from immunoglobulin G heavy chain, and the terminal Pro-Gly-Pro is the addition that defines the analogue.
That tail is the whole design idea. Free tuftsin is cleared quickly by amino and carboxypeptidases, and the proline-rich extension blocks the C-terminal approach, lengthening the half-life in plasma preparations. The formula contains no sulfur, so oxidation is not the dominant degradation route, while the lysine and arginine give the molecule a strong positive charge and very good water solubility.
Published work uses Selank chiefly in rodent behavioural pharmacology, in anxiety-like and stress paradigms, and in cell and tissue work on gamma-aminobutyric acid receptor expression, monoamine turnover and enkephalin-degrading enzyme activity. Its immunological heritage also shows up in studies of interleukin expression. No single receptor has been established as the primary target, the contribution of the tuftsin portion is unresolved, and much of the behavioural literature comes from a narrow group of laboratories.
Reconstitution & handling
Sterile or bacteriostatic water dissolves this peptide easily, and gentle swirling clears the cake. Add the diluent slowly down the vial wall to avoid foaming. Concentration is the labelled peptide mass divided by the volume of water added, and the net peptide content figure on the certificate should be used where molarity rather than nominal mass matters.
Storage & stability
Keep the sealed lyophilized vial at -20 °C, desiccated and away from light. The powder is hygroscopic because of its basic residues, so let a cold vial warm before opening it. Reconstituted solution holds at 2 to 8 °C and should be split into single-use aliquots. Short, highly charged peptides also adsorb to container surfaces, so low-binding tubes help when a dilute stock has to stand.
How it's tested
Reversed-phase HPLC at 214 and 220 nm carries the purity determination, since this sequence has no strongly absorbing aromatic side chain to read at 280 nm. Identity is confirmed by mass spectrometry against the theoretical average mass of 751.88. Net peptide content, water and residual acetate are reported alongside purity, and the lot-matched certificate of analysis is available on request.