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Voltage-dependent behavior of a "ball-and-chain" gramicidin channel
Woolley, G. Andrew Zunic, Valentin Karanicolas, John Jaikaran, Anna S. I. Starostin, Andrei V.
Woolley, G. Andrew
Zunic, Valentin
Karanicolas, John
Jaikaran, Anna S. I.
Starostin, Andrei V.
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Abstract
The channel-forming properties of two analogs of gramicidin, gramicidin-ethylenediamine (gram-EDA), and gramicidin-N,N-dimethylethylenediamine (gram-DMEDA) were studied in planar lipid bilayers, using protons as the permeant ion. These peptides have positively charged amino groups tethered to their C-terminal ends via a linker containing a carbamate group. Gram-DMEDA has two extra methyl groups attached to the terminal amino group, making it a bulkier derivative. The carbamate groups undergo thermal cis-trans isomerization on the 10–100-ms time scale. The conductance behavior of gram-EDA is found to be markedly voltage dependent, whereas the behavior of gram-DMEDA is not. In addition, voltage affects the cis-trans ratios of the carbamate groups of gram-EDA, but not those of gram-DMEDA. A model is proposed to account for these observations, in which voltage can promote the binding of the terminal amino group of gram-EDA to the pore in a "ball-and-chain" fashion. The bulkiness of the gram-DMEDA derivative prevents this binding.
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This is the published version. Copyright 1997 by Elsevier.
Date
1997-11
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The Biophysical Society
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Woolley, G.a., V. Zunic, J. Karanicolas, A.s. Jaikaran, and A.v. Starostin. "Voltage-dependent Behavior of a "ball-and-chain" Gramicidin Channel." Biophysical Journal 73.5 (1997): 2465-475. http://dx.doi.org/10.1016/S0006-3495(97)78275-4.