Ionic channels of some glycine-rich synthetic polypeptides

Abstract

The ion transport properties of glycine-rich synthetic polypeptides (Ser-Leu-Gly)n, (Leu-Ser-Leu-Gly)n and their O-benzyl derivatives have been examined. When incorporated into lipid bilayers membranes, all these model molecules give rise to ion permeation through single channel events. Their behavior, peculiarly that of the O-protected derivatives rules out the channeled model previously proposed for (Leu-Ser-Leu-Gly)n in which the hydroxyl groups of the seryl residues were supposed to play a role in the ion translocation process. This latter polypeptide also permeates membranes to calcium. Preliminary investigations suggest an α-like helical conformation rather than a β helix with an intramolecular channel.