Combination of the electrogenic ionophores, valinomycin and CCCP, can lead to non-electrogenic K+/H+ exchange on bilayer lipid membranes.
The method of pH shift measuring by means of a pH microelectrode was applied to measure hydrogen ion fluxes across a planar bilayer lipid membrane (BLM) in the presence of the potassium ion ionophore, valinomycin, and a protonophore, carbonylcyanide m-chlorophenylhydrazone (CCCP), under conditions of the voltage clamp. The voltage dependence of the flux was determined to be in the range of +/- 150 mV under the conditions of both symmetrical KCl as well as a KCl gradient across the BLM. Surprisingly, at a clamped zero voltage on BLM a significant hydrogen ion flux was observed in the presence of a KCL gradient and both valinomycin and CCCP. This finding was interpreted as a result of induction of non-electrogenic K+/H+ exchange in the presence of valinomycin and CCCP, presumably through the formation of electrically neutral complexes of these two ionophores and K+ (H+) ions: valinomycin-K(+)-CCCP- and/or possibly valinomycin-CCCP(-)-H+.
Orlov
V N
VN
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow, Russian Federation.
Antonenko
Y N
YN
Bulychev
A A
AA
Yaguzhinsky
L S
LS
D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000737:chemistry*; D006096:Gramicidin; D006859:Hydrogen; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008051:Lipid Bilayers; D008954:Models, Biological; D011188:Potassium; D011189:Potassium Chloride; D014634:Valinomycin / Q000737:chemistry*
D008051:Lipid Bilayers; D006096:Gramicidin; D014634:Valinomycin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D011189:Potassium Chloride; D006859:Hydrogen; D011188:Potassium