Solid-state 23Na NMR determination of the number and coordination of sodium cations bound to Oxytricha nova telomere repeat d(G4T4G4) |
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Authors: | Wu Gang Wong Alan |
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Institution: | Department of Chemistry, Queen's University, Kingston, Ont., Canada K7L 3N6. gangwu@chem.queensu.ca |
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Abstract: | We report a solid-state (23)Na NMR study of the bound sodium cations in a G-quadruplex formed by Oxytricha nova telomere DNA repeat, d(G(4)T(4)G(4)) (Oxy-1.5). Using a 2D multiple-quantum magic-angle spinning (23)Na NMR method, we observed three sodium cations residing inside the quadruplex channel of the Na(+) form of Oxy-1.5. Each of these sodium cations is sandwiched between two G-quartets. We found no evidence for sodium cations in the T(4) loop region. For comparison, solid-state (15)N MAS NMR spectra were also obtained for the (15)NH(4)(+) form of Oxy-1.5. The insufficient resolution in the (15)N MAS NMR spectra did not permit determination of the number of NH(4)(+) ions inside the quadruplex channel. The solid-state (23)Na and (15)N NMR spectra for Oxy-1.5 were also compared with those obtained for guanosine 5'-monophosphate. |
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Keywords: | Alkali metal Cation binding G-quartet Solid-state NMR Telomeric DNA |
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