title: The C- and N-Terminal Residues of Synthetic Heptapeptide Ion Channels Influence Transport Efficacy Through Phospholipid Bilayers.
abstract: 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.
authors.affiliation: Department of Molecular Biology & Pharmacology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8103, St. Louis, MO 63110 U. S. A.
authors.forename: Natasha
authors.initials: N
authors.lastname: Djedovič
authors.forename: Riccardo
authors.initials: R
authors.lastname: Ferdani
authors.forename: Egan
authors.initials: E
authors.lastname: Harder
authors.forename: Jolanta
authors.initials: J
authors.lastname: Pajewska
authors.forename: Robert
authors.initials: R
authors.lastname: Pajewski
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Weber
authors.forename: Paul H
authors.initials: PH
authors.lastname: Schlesinger
authors.forename: George W
authors.initials: GW
authors.lastname: Gokel