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

Publication Type	Academic Article
Authors	Hinton J, Whaley W, Shungu D, Koeppe R, Millett F
Journal	Biophys J
Volume	50
Issue	3
Pagination	539-44
Date Published	09/01/1986
ISSN	0006-3495
Keywords	Gramicidin
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.
DOI	10.1016/S0006-3495(86)83492-0
PubMed ID	2428415
PubMed Central ID	PMC1329731