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. 1986 Sep;50(3):539–544. doi: 10.1016/S0006-3495(86)83492-0

Equilibrium binding constants for the group I metal cations with gramicidin-A determined by competition studies and T1+-205 nuclear magnetic resonance spectroscopy.

J F Hinton, W L Whaley, D Shungu, R E Koeppe 2nd, F S Millett
PMCID: PMC1329731  PMID: 2428415

Abstract

The equilibrium binding constants of the Group I metal cations with gramicidin A in aqueous dispersions of lyso-PC have been determined using a combination of competitive binding with the T1+ ion and T1-205 NMR spectroscopy. The values of the binding constants at 34 degrees C are Li (32.2 M-1), Na (36.9 M-1), K (52.6 M-1), Rb (55.9 M-1), and Cs (54.0 M-1). The equilibrium binding constant for the T1+ ion at this temperature is 582 M-1. The relationships between the binding constants, the free energy of the binding process, and the cation selectivity of the gramicidin A channel are discussed.

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Selected References

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