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NMR structure and dynamic studies of an anion-binding, channel-forming heptapeptide.

Cook GA, Pajewski R, Aburi M, Smith PE, Prakash O, Tomich JM, Gokel GW

Departments of Biochemistry and Chemistry, Kansas State University, Manhattan, Kansas 66506, USA.

The synthetic peptide (C(18)H(37))(2)NCOCH(2)OCH(2)CON-(Gly)(3)-Pro-(Gly)(3)-OCH(2)Ph forms chloride-selective channels in liposomes and exhibits voltage-gating properties in planar phospholipid bilayers. The peptide fragment of the channel is based on a conserved motif in naturally occurring chloride transporters. Membrane-anchoring residues at the N- and C-terminal ends augment the peptide. NMR spectra (1D and 2D) of the channel in CDCl(3) showed significant variation in the absence and presence of stoichiometric tetrabutylammonium chloride (Bu(4)NCl). One-dimensional solution-state NMR titration studies combined with computational molecular simulation studies indicate that the peptide interacts with the salt as an ion pair and H-bonds chloride. To our knowledge, this is the first structural analysis of any synthetic anion-channel salt complex.

Published 1 February 2006 in J Am Chem Soc, 128(5): 1633-8.
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