title: Cation binding in Na,K-ATPase, investigated by 205Tl solid-state NMR spectroscopy.
abstract: Cation binding to Na,K-ATPase is characterized in native membranes at room temperature by solid-state NMR spectroscopy using the K(+) congener (205)Tl. It has been demonstrated that the signals from occluded Tl(+) and nonspecifically bound Tl(+) can be detected and distinguished by NMR. Effects of dipole-dipole coupling between (1)H and (205)Tl in the occlusion sites show that the ions are rigidly bound, rather than just occluded. Furthermore, a low chemical shift suggests occlusion site geometries with a relatively small contribution from carboxylate and hydroxyl groups. Nonspecific binding of Tl(+) is characterized by rapid chemical exchange, in agreement with the observed low binding affinity.
authors.affiliation: Department of Biophysics, Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus, Denmark.
authors.forename: Louise Odgaard
authors.initials: LO
authors.lastname: Jakobsen
authors.forename: Anders
authors.initials: A
authors.lastname: Malmendal
authors.forename: Niels Chr
authors.initials: NC
authors.lastname: Nielsen
authors.forename: Mikael
authors.initials: M
authors.lastname: Esmann
mesh_terms: D000818:Animals; D001665:Binding Sites; D002412:Cations / Q000737:chemistry*; D066298:In Vitro Techniques; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008566:Membranes / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry*; D011485:Protein Binding; D012491:Salt Gland / Q000201:enzymology; D012754:Sharks; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry*; D013552:Swine
chemical_list: D002412:Cations; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium