Overview

Selank is a peptide chain composed of two fragments – one is Tuftsin at the N-terminus, and the other is a tripeptide Pro-Gly-Pro (PGP) at the C-terminal end of the molecule. The inclusion of a Pro-Gly-Pro (PGP) sequence in the peptide Selank might enhance its potential to penetrate various biological barriers, including the blood-brain barrier (BBB). The BBB is a highly selective and semi-permeable membrane that delineates the circulating blood from brain tissues and extracellular fluid within the central nervous system. It is deemed to play a pivotal role in controlling the entry of molecules. Integrating the PGP sequence might modify the peptide’s hydrophilicity or lipophilicity, which might increase its compatibility with the lipid-rich milieu of the BBB. Moreover, the PGP motif might interact with certain transport systems or receptors on the BBB membrane, potentially facilitating receptor-mediated endocytosis or active transport. These mechanisms may permit Selank to circumvent the tight junctions that typically impede the transit of larger molecules through the BBB. Additionally, the presence of the PGP sequence might alter the tertiary structure of Selank, potentially rendering it more amenable to traversing the BBB. This alteration might arise from changes in the peptide’s spatial configuration, which may influence its interaction with the cellular components of the BBB.⁽⁶⁾