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Type of Publication: | Journal article |
URI (citable link): | http://nbn-resolving.de/urn:nbn:de:bsz:352-0-292115 |
Author: | Tashkin, Vsevolod Yu.; Gavrilchik, A.N.; Ilovaisky, Alexey I.; Apell, Hans-Jürgen; Sokolov, Valeriy S. |
Year of publication: | 2015 |
Published in: | Biochemistry (Moscow) Supplement Series A : Membrane and Cell Biology ; 9 (2015), 2. - pp. 92-99. - ISSN 1990-7478. - eISSN 1990-7494 |
DOI (citable link): | https://dx.doi.org/10.1134/S1990747815020105 |
Summary: |
Electrogenic binding of ions from the cytoplasmic side of the Na+,K+-ATPase has been studied by measurements of changes of the membrane capacitance and conductance triggered by a jump of pH or of the sodium-ion concentration in the absence of ATP. The pH jumps were performed in experiments with membrane fragments containing purified Na+,K+-ATPase adsorbed to a bilayer lipid membrane (BLM). Protons were released in a sub-millisecond time range from a photosensitive compound (caged H+) triggered by a UV light flash. The sodium concentration jumps were carried out by a fast solution exchange in experiments with membrane fragments attached to a solid-supported membrane deposited on a gold electrode. The change of the membrane capacitance triggered by the pH jump depended on the sodium-ion concentration. Potassium ions had a similar effect on the capacitance change triggered by a pH jump. The effects of these ions are explained by the their competition with protons in the binding sites on cytoplasmic side of the Na+,K+-ATPase. The approximation of the experimental data by a theoretical model yields the dissociation constants, K, and the cooperativity coefficients, n, of the binding sites for sodium ions (K = 2.7 mM, n = 2) and potassium ions (K = 1.7 mM, n = 2). In the presence of magnesium ions the apparent dissociation constants of sodium increased. A possible reason of the inhibition of sodium-ion binding by magnesium ions can be an electrostatic or conformational effect of magnesium ions bound to a separate site of the Na+,K+-ATPase close to the entrance to the sodium-ion binding sites.
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Subject (DDC): | 570 Biosciences, Biology |
Keywords: | sodium pump, electrogenic ion transport, Na+,K+-ATPase, caged H+, solid-supported membranes |
Link to License: | In Copyright |
Bibliography of Konstanz: | Yes |
TASHKIN, Vsevolod Yu., A.N. GAVRILCHIK, Alexey I. ILOVAISKY, Hans-Jürgen APELL, Valeriy S. SOKOLOV, 2015. Electrogenic Binding of Ions at the Cytoplasmic Side of the Na+,K+-ATPase. In: Biochemistry (Moscow) Supplement Series A : Membrane and Cell Biology. 9(2), pp. 92-99. ISSN 1990-7478. eISSN 1990-7494. Available under: doi: 10.1134/S1990747815020105
@article{Tashkin2015Elect-31504, title={Electrogenic Binding of Ions at the Cytoplasmic Side of the Na+,K+-ATPase}, year={2015}, doi={10.1134/S1990747815020105}, number={2}, volume={9}, issn={1990-7478}, journal={Biochemistry (Moscow) Supplement Series A : Membrane and Cell Biology}, pages={92--99}, author={Tashkin, Vsevolod Yu. and Gavrilchik, A.N. and Ilovaisky, Alexey I. and Apell, Hans-Jürgen and Sokolov, Valeriy S.} }
Tashkin_0-292115.pdf | 288 |