What Selank is
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its first four residues are tuftsin, a naturally occurring fragment of the heavy chain of immunoglobulin G that has been studied since the 1970s for its activity on phagocytic cells. To that tetrapeptide the designers added the tripeptide Pro-Gly-Pro, a motif chosen because it resists cleavage by the peptidases that otherwise degrade short peptides within minutes, and because Pro-Gly-Pro itself had been reported to have activity in the central nervous system.
The compound was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, the same group responsible for Semax, and most of the primary literature is Russian in origin, with a portion of it available in English translation. The molecular weight is approximately 752 g/mol and the CAS number is 129954-34-3. Selank belongs to the neuropeptides and other class.
The published literature on the compound, with references, is collected in the monograph.
What you receive
Each vial contains Selank as a white lyophilised powder, sealed with a flip-off cap over a crimped stopper, in the net quantity stated on the label: 10 mg. There is no carrier, mannitol or other excipient unless the batch certificate says otherwise. The batch number is printed on the label and matches the certificate in our register.
Reading the certificate for a Selank batch
Purity by reversed-phase HPLC is reported as the area of the main peak against all peaks and should be above 99% for a seven-residue peptide. Identity by LC-MS is reported as the observed mass against the expected mass of about 752 Da, usually visible as both the singly charged ion near 753 and the doubly charged ion near 377. Net content gives the milligrams of peptide actually present, as distinct from the nominal fill.
The impurities to expect are deletion sequences missing one proline, which are 97 Da lighter, and a small amount of the Thr-Lys diketopiperazine. Selank has no methionine, cysteine or tryptophan, so oxidation products are not usually an issue. Our guide to reading a certificate of analysis walks through annotated examples, and HPLC and LC-MS explained covers the methods.
Storage and handling
Sealed vials should be kept refrigerated at 2 to 8 °C and protected from light; −20 °C is preferable beyond a few months. Short basic peptides are hygroscopic, so allow the vial to reach room temperature before opening and reseal promptly. The absence of oxidisable residues makes the dry powder stable for well over a year. Selank dissolves readily in water or buffer; solutions are best prepared fresh or aliquoted and frozen, as the storage and stability guide explains.