Thermodynamic parameters for the binding of divalent cations to gramicidin A incorporated into a lipid environment by Tl-205 nuclear magnetic resonance.

Publication Type	Academic Article
Authors	Hinton J, Fernandez J, Shungu D, Millett F
Journal	Biophys J
Volume	55
Issue	2
Pagination	327-30
Date Published	02/01/1989
ISSN	0006-3495
Keywords	Gramicidin, Lipid Bilayers, Lysophosphatidylcholines, Models, Biological
Abstract	Thermodynamic parameters, enthalpy and entropy, for the binding of the divalent cations, Mg+2, Ca+2, Sr+2, Ba+2, and Cd+2, to gramicidin A, incorporated into lysophosphatidylcholine, have been determined using a combination of Tl-205 nuclear magnetic resonance spectroscopy and competition binding. The binding process is thermodynamically driven by the enthalpy and not the entropy. The enthalpy values are related to the process involving the transfer of cations from an aqueous environment to an amide environment. A comparison is made between the thermodynamic parameters for the binding of monovalent and divalent cations to gramicidin A to illustrate the channel blocking ability of the divalent cations with respect to monovalent cation transport.
DOI	10.1016/S0006-3495(89)82808-5
PubMed ID	2469486
PubMed Central ID	PMC1330474