23Na-nuclear magnetic resonance investigation of gramicidin-induced ion transport through membranes under equilibrium conditions.

Publication Type	Academic Article
Authors	Buster D, Hinton J, Millett F, Shungu D
Journal	Biophys J
Volume	53
Issue	2
Pagination	145-52
Date Published	02/01/1988
ISSN	0006-3495
Keywords	Gramicidin, Ion Channels, Lipid Bilayers, Phosphatidylcholines, Phosphatidylglycerols
Abstract	A technique for investigating the gramicidin-facilitated transport of Na+ ions across lipid bilayers of large unilamellar vesicles under the condition of ionic equilibrium has been developed using a combination of heat incubation of the gramicidin with the vesicles and 23Na-nuclear magnetic resonance (NMR) spectroscopy. Isolation of the two 23Na-NMR signals from the intra- and extravesicular Na+ with the shift reagent, dysprosium (III) tripolyphosphate, allows the equilibrium flux of Na+ through the gramicidin channels to be detected and treated as a two-site exchange process. This study indicates that the transport of Na+ through gramicidin channels is second order with respect to the gramicidin concentration.
DOI	10.1016/S0006-3495(88)83076-5
PubMed ID	2449917
PubMed Central ID	PMC1330135