Determination of the structure of a membrane-incorporated ion channel. Solid-state nuclear magnetic resonance studies of gramicidin A

Smith R., Thomas D.E., Separovic F., Atkins A.R. and Cornell B.A. (1989) Determination of the structure of a membrane-incorporated ion channel. Solid-state nuclear magnetic resonance studies of gramicidin A. Biophysical Journal, 56 2: 307-314. doi:10.1016/S0006-3495(89)82677-3


Author Smith R.
Thomas D.E.
Separovic F.
Atkins A.R.
Cornell B.A.
Title Determination of the structure of a membrane-incorporated ion channel. Solid-state nuclear magnetic resonance studies of gramicidin A
Journal name Biophysical Journal   Check publisher's open access policy
ISSN 0006-3495
Publication date 1989-01-01
Sub-type Article (original research)
DOI 10.1016/S0006-3495(89)82677-3
Volume 56
Issue 2
Start page 307
End page 314
Total pages 8
Language eng
Subject 1304 Biophysics
Abstract Solid-state nuclear magnetic resonance (NMR) measurements on 13C-labeled analogues of the ion channel-forming peptide, gramicidin A, have been used to directly determine the structure of this peptide in lipid membranes. Seven gramicidin analogues, each labeled in a single carbonyl group of gly2, L-ala3, D-leu4, L-val7, D-leu10, D-leu12, or D-leu14 were synthesized by the solid-phase method. These gramicidin analogues were incorporated into aligned multilayers of dimyristoylphosphatidylcholine, or diether lipid bearing 14- or 16-carbon chains, at a 1:15 peptide:lipid mole ratio. Proton-enhanced, 13C, solid-state spectra were obtained at several temperatures and over a range of sample orientations with respect to the spectrometer magnetic field to permit accurate measurement of the chemical shift anisotropies. The observed anisotropies indicate that all of the labeled carbonyl bonds are oriented almost parallel to the molecular long axis and perpendicular to the lipid bilayer plane. These orientations are consistent with gramicidin forming a beta 6.3 single-strand helix that is oriented parallel to the methylene chains of the lipid molecules. Comparison of the linewidths from labeled residues that are in the innermost turn of the helix (gly2, ala3, and D-leu4), in the center of the molecule (val7), and in the turn nearest the lipid bilayer surface (D-leu10, D-leu12, and D-leu14) suggests that although the peptide behaves largely as a rigid barrel, segments of the peptide close to the membrane surface possess greater motional freedom.(ABSTRACT TRUNCATED AT 250 WORDS)
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
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