Replacing proline at the apex of heptapeptide-based chloride ion transporters alters their properties and their ionophoretic efficacy

A membrane anchored heptapeptide, (C18H37)(2)NHCOCH2OCH2CO-NH-Gly-Gly-Gly-Pro-Gly-Gly-Gly-OCH2Ph, has proved to be a selective chloride anion transporter that functions in phospholipid bilayer membranes. When Pro was replaced by the natural amino acid Leu, the activity decreased dramatically. In the present study, Pro is replaced by pipecolic acid (homoproline, Pip); the resulting anchored heptapeptide is a membrane active, chloride selective transporter.