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Djedovic N, Ferdani R, Harder E, Pajewska J, Pajewski R, Weber ME, Schlesinger PH, Gokel GW: The C- and N-Terminal Residues of Synthetic Heptapeptide Ion Channels Influence Transport Efficacy Through Phospholipid Bilayers. New J Chem. 2005 Jan 1;29(2):291-305.
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. The compounds having varied N-terminal anchors and C-terminal benzyl groups are as follows: 1, R = n-propyl; 2, R = n-hexyl; 3, R = n-octyl; 4, R = n-decyl; 5, R = n-dodecyl; 6, R = n-tetradecyl; 7, R = n-hexadecyl; 8, R = n-octadecyl. Compounds 9-19 have R = n-octadecyl and C-terminal residues as follows: 9, OR' = OCH (2) CH (3); 10, OR' = OCH (CH (3))(2); 11, OR' = O (CH (2))(6) CH (3); 12, OR' = OCH (2)-c-C (6) H (11); 13, OR' = O (CH (2))(9) CH (3); 14, OR' = O (CH (2))(17) CH (3); 15, NR'(2) = N [(CH (2))(6) CH (3)](2); 16, NHR' = NH (CH (2))(9) CH (3); 17, NR'(2) = N [(CH (2))(9) CH (3)](2); 18, NHR' = NH (CH (2))(17) CH (3); 19, NR'(2) = N [(CH (2))(17) CH (3)](2). The highest anion transport activities were observed as follows. For the benzyl esters whose N-terminal residues were varied, i.e.1-8, compound 3 was most active. For the C (18) anchored esters 10-14, n-heptyl ester 11 was most active. For the C (18) anchored, C-terminal amides 15-19, di-n-decylamide 17 was most active. It was concluded that both the C- and N-terminal anchors were important for channel function in the bilayer but that activity was lost unless only one of the two anchoring groups was dominant. |
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