Solid-state 13C-NMR studies of the effects of sodium ions on the gramicidin A ion channel.
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.
Smith
R
R
Biochemistry Department, University of Queensland, Brisbane, Australia.
Thomas
D E
DE
Atkins
A R
AR
Separovic
F
F
Cornell
B A
BA
D004134:Dimyristoylphosphatidylcholine; D006096:Gramicidin; D066298:In Vitro Techniques; D007473:Ion Channels / Q000648:ultrastructure*; D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D011487:Protein Conformation; D012964:Sodium / Q000494:pharmacology*; D013329:Structure-Activity Relationship
D007473:Ion Channels; D008051:Lipid Bilayers; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D006096:Gramicidin; D012964:Sodium; D004134:Dimyristoylphosphatidylcholine