Nucleic acids relaxation parameters

See also Chemical Exchange Effects in NMR Mac-romolecule-Ligand Interactions Studied By NMR NMR in Anisotropic Systems, Theory NMR Principles NMR Relaxation Rates Nucleic Acids Studied Using NMR Parameters in NMR Spectroscopy, Theory of Structural Chemistry using NMR Spectroscopy, Organic molecules. 

Some 2 P relaxation data for nucleic acids have been analyzed assuming the motion governing relaxation is simple isotropic motion, but usually it is necessary to consider the motion of nucleic acids as being more complicated. Generally, one calculates relaxation parameters using spectral densi-... 

Figure 6 shows some of the possible motions in double-stranded nucleic acids that may affect NMR relaxation parameters. The end-for-end tumbling and speedometer-cable rotation depicted in Fig. 6 become rotation around the short axis and around the long axis of the cylinder, if the nucleic acid is sufficiently short. Transient electric dichroism studies of rodlike DNA molecules have provided data about the end-for-end rotational diffusion (Hogan et al, 1978). In contrast, not much experimental data are available for the speedometer-cable motion. 

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