Solution phase synthesis and purification of the minigramicidin ion channels and a succinyl-linked gramicidin

Peptides with alternating D- and L-configured residues as found in the natural ion channel active peptide gramicidin A (gA) are important building blocks for artificially engineered ion channels. We detail an optimised solution phase synthesis employing a convergent assembly of peptide building blocks, giving access to the minigramicidines and a succinyl linked gA derivative on preparative scale. Moreover, the minigramicidines were investigated for secondary structure formation by CD-spectroscopy. which was discovered to be medium and capping-group dependent. A parallel, left-handed double-beta-helix seems to be generally favoured in organic solvents for the minigramicidines. (C) 2002 Elsevier Science Ltd. All rights reserved.