Effect of Counter Ions on Cross-Correlated Relaxation Rates in Nucleic Acids
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Proceedings |
| Conference | XXIII International Conference on Magnetic Resonance in Biological Systems |
| MU Faculty or unit | |
| Citation | |
| Field | Biophysics |
| Keywords | NMR; nucleic acids;structure;dynamics |
| Description | Studies of biomolecular structure and dynamics based on relaxation rates and induced chemical shifts generally assume that the chemical shift tensors for a particular type of nucleus are constant and independent of experimental conditions. We tested the validity of the assumption for different counterion types and ionic strengths in an extraordinary stable DNA hairpin d(GCGAAGC)by measuring cross-correlated relaxation rates between the 13C chemical shift tensor and the 1H-13C dipole-dipole interaction of protonated base carbons. The results indicate that the type of the counter-ion strongly influences the magnitude as well as the orientation of the chemical shielding tensors in nucleic acid bases. A proper and physically meaningful interpretation of NMR observables reflecting chemical shielding anisotropy and/or chemical shielding tensor orientation should therefore account for the composition of the NMR buffer. |
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