The C- and N-Terminal Residues of Synthetic Heptapeptide Ion Channels Influence Transport Efficacy Through Phospholipid Bilayers.

The synthetic peptide, R(2)N-COCH(2)OCH(2)CO-Gly-Gly-Gly-Pro-Gly-Gly-Gly-OR', was shown to be selective for Cl(-) over K(+) when R is n-octadecyl and R' is benzyl. Nineteen heptapeptides have now been prepared in which the N-terminal and C-terminal residues have been varied. All of the N-terminal residues are dialkyl but the C-terminal chains are esters, 2 degrees amides, or 3 degrees amides.

Pore formation in and enlargement of phospholipid liposomes by synthetic models of ceramides and sphingomyelin.

A family of compounds having twin octadecyl anchor chains and various polar headgroups were designed to be ceramide mimics. The compounds prepared increase the apparent permeability of phospholipid vesicles to chloride and carboxyfluorescein anions. In addition, significantly larger vesicles are observed after exposure to these compounds suggesting the possibility of vesicular fusion.

The C-terminal ester of membrane anchored peptide ion channels affects anion transport.

Five heptapeptide derivatives, [CH3(CH2)17]2NCOCH2OCH2CO-Gly-Gly-Gly-Pro-Gly-Gly-Gly-OR, in which R = ethyl, 2-propyl, heptyl, benzyl, and cyclohexylmethyl, were found to transport chloride anion through a phospholipid bilayer to varying extents dependent on the identity of R. It was concluded that the R group is a membrane anchor for the synthetic chloride channels.