Related Experiment Video
Updated: Sep 3, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Determination of fast dynamics of nucleic acids by NMR
1Division of Molecular Structure, National Institute for Medical Research, London, United Kingdom.
Abstract:
Double-stranded oligonucleotides of < 10 base pairs are adequately described as an isotropic rotor, using the correlation time for the cytosine H6-H5 vector. For longer fragments, the cylindrical model should be used for detailed analysis of NOEs. The appropriate correlation times can be calculated using the formulae of Tirado and Garcia de la Torre or derived from measurements of the cross-relaxation rate constants for cytosine (or uridine) H6-H5. Order parameters describing the degree of motion of different vectors on the subnanosecond time scale vary substantially, with typical values of S2 > 0.8 for base vectors and 0.5-0.8 for intrasugar and base-sugar vectors. Order parameters for terminal nucleotides are typically significantly smaller than for internal nucleotides, which may also mean that their conformation will be less well determined in the formalism of a unique structure. The CSA relaxation rates of the phosphodiesters appear to be insensitive to internal motions and may, therefore, provide the most accurate estimate of the overall tumbling time in nucleic acid fragments. Using a combination of relaxation data for different nuclei and different spectrometer frequencies may be expected to yield detailed information about fast motions in nucleic acid fragments.
Related Concept Videos
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
¹H NMR of Labile Protons: Temporal Resolution
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
NMR Spectrometers: Resolution and Error Correction
Applications Of NMR In Biology
The...
Atomic Nuclei: Types of Nuclear Relaxation
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...

