Thermodynamic parameters for the binding of divalent cations to gramicidin A incorporated into a lipid environment by Tl-205 nuclear magnetic resonance
Related Experiment Video
Updated: Oct 22, 2026

Gramicidin-based Fluorescence Assay; for Determining Small Molecules Potential for Modifying Lipid Bilayer Properties
Published on: October 13, 2010
J F Hinton1, J Q Fernandez, D C Shungu
1Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville 72701.
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.
Related Concept Videos
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
The Equilibrium Binding Constant and Binding Strength
EDTA: Conditional Formation Constant
For the equilibrium reaction of the metal with the Y4− form of EDTA, the formation...

