Solid-state 13C-NMR studies of the effects of sodium ions on the gramicidin A ion channel. |
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| Authors: | R Smith D E Thomas A R Atkins F Separovic B A Cornell |
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| Institution: | Biochemistry Department, University of Queensland, Brisbane, Australia. |
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| Abstract: | End-to-end helical dimers of gramicidin A form transmembrane pores in lipid bilayers, through which monovalent ions may pass. The groups within the peptide that interact with these ions have been studied by application of solid-state spectroscopic methods to a series of gramicidin A analogues synthesized with 13C in selected peptide carbonyl groups. The resonances of D-Leu10, D-Leu12 and D-Leu14 analogues were perturbed in the presence of 0.16 M sodium ions, whereas the resonances of the carbonyls of Gly2, Ala3, D-Leu4 and Val7, which are closer to the formylated N-terminal end of the peptide, were unaffected. The observed changes in chemical shift anisotropy are indicative of a change in orientation of the abovementioned leucine carbonyls. |
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