Effect of Na+, K+, Mg2+ and ATP on the Relative Electrophoretic Mobility of Sugar Beet Membrane Particles with NaK ATPase Activity |
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Authors: | JAN KARLSSON |
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Institution: | Botanical Institute, University of Stockholm, Lilla Frescati, S-104 05 Stockholm, Sweden |
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Abstract: | Electrophoretic measurements on membrane coated particles were performed with a Zytopherometer. Tris-HCl buffer 0.2 M pH 7.0 at 37°C with addition of different combinations of Na+, K+, Mg2+ and ATP was used as test medium. The membranes were of two types, an untreated preparation with low NaK ATPase activity and a deoxycholate treated preparation with high NaK ATPase activity. There was no marked difference in reaction between the two types of membranes. To both types of membranes Mg2+ gave a strong positive and ATP a slight negative addition to the membrane charge. In the presence of ATP Na+ gave a higher charge contribution than did K+ or a combination of Na+ and K+. This implies that K+ gives a higher affinity for ATP than Na+ does and or that ATP mediates a higher affinity for Na+ than for K+. |
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