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Proton dissociation from nigericin at the membrane—water interface, the rate‐limiting step of K + /H + exchange on the bilayer lipid membrane
Author(s) -
Kovbasnjuk Olga N.,
Antonenko Yuri N.,
Yaguzhinsky Lev S.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81063-e
Subject(s) - nigericin , dissociation (chemistry) , chemistry , membrane , limiting , proton , lipid bilayer , biophysics , nuclear physics , biochemistry , physics , mechanical engineering , engineering , biology
The rate of K + /H + exchange through bilayer lipid membranes (BLM) induced by nigericin was measured by the method of pH gradient offset according to Antonenko, Yu.N. and Yaguzhinsky L.S. [(1990) Biochim. Biophys. Acta 1026, 236–240]. It was shown that under the conditions of high potassium ion concentration the rate of nigericin‐mediated K + /H + exchange increased with an increase in the concentrations of such buffer compounds as citric acid and MES. The concentration dependence was different for citrate and MES. The buffer concentration effect was absent at low potassium ion concentrations. Citrate increased the rate of K + /H + exchange being added to the side of BLM where the K + concentration was higher and had no effect at the opposite side. At High KCl and citrate concentrations, the rate of K + /H + exchange was about 6 times lower in D 2 O when compared to H 2 O solutions. It is concluded that under certain experimental conditions the overall rate of the K + /H + exchange induced by nigericin is determined by the rate of proton dissociation from nigericin at the membrane—water interface.