Sodium-23 nuclear magnetic resonance studies of cation-deoxyribonucleic acid interactions

Effective interaction between helical biomolecules

“…The actual data are consistent with Manning's condensation parameter [82,83] θ 0 = λ/|q c |λ B = 0.71 particularly if the width δ is taken as one Bjerrum length. Our data are also in semiquantitative accordance with other computer simulations [38] and nuclear magnetic resonance (NMR) experiments which show that the condensed counterion fractions are in the range of 0.65 to 0.85 [84] or 0.53 to 0.57 [85,45]. , dp = 0.2Å), dot-dashed line-run B (dc = 2Å, dp = 2Å), dashed line-run C (dc = 2Å, dp = 6Å).…”

Role and Applications of Electrostatic Effects on Nucleic Acid Conformational Transitions and Binding Processes

“…23 Na longitudinal and transverse relaxation rates (R obs ) are independent of NA sequence and much larger in "salt-free" DNA-containing samples than in otherwise comparable solutions lacking DNA (Braunlin, 1995). The extent of Na + association is temperature independent within the 6 -33 °C range tested, as would be expected if accumulation was due to exclusively electrostatic interactions (Bleam et al, 1983). R obs has been described in terms of a two-state model in which sodium ions are considered either "bound" to the DNA or "free."…”

The Influence of Water Content on the 23Na and 31P NMR Spectral Parameters in Solid Na-DNA

“…The solution was sonicated using a Misonix XL-2020 sonicator with output frequency of 20 kHz for 3 min at 48C, with bursts of 10 s duration separated by 10 s pauses to avoid overheating. Under these conditions the average DNA chain length distribution expressed in terms of molecular weight is in the range 1-2 Â 10 6 [11,20]. The sonicated solution was dialysed at 48C [11], first against a 0:01 M solution of Na 3 EDTA (pH 8) to remove polyvalent cations, then twice against 0:1 M NaCl and 0:01 M Tris buffer (pH 8).…”

“…Under these conditions the average DNA chain length distribution expressed in terms of molecular weight is in the range 1-2 Â 10 6 [11,20]. The sonicated solution was dialysed at 48C [11], first against a 0:01 M solution of Na 3 EDTA (pH 8) to remove polyvalent cations, then twice against 0:1 M NaCl and 0:01 M Tris buffer (pH 8). Finally, five dialyses against a 0:01 M solution of NaCl (pH 7) were carried out.…”

“…The preferred DNA conformation depends on the particular DNA base sequence and on the activity of water. The most common B form of DNA in solution has been extensively studied by NMR in an attempt to understand its conformation and the influence of monovalent and divalent ions on the structure [5][6][7][8][9][10][11]. Intercalation in DNA has been studied via the measurement of 23 Na and 7 Li spin-lattice relaxation times [12,13].…”