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Biophys J. 1986 Sep;50(3):539-44.

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

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.

PMID:
2428415
PMCID:
PMC1329731
DOI:
10.1016/S0006-3495(86)83492-0
[Indexed for MEDLINE]
Free PMC Article

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