Journal ArticleDOI
Dipolar relaxation and nuclear Overhauser effects in nonrigid molecules: The effect of fluctuating internuclear distances
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TLDR
In this article, a simple treatment of dipolar contribution to nuclear magnetic relaxation is developed for molecules in which conformational fluctuations modulate the relevant internuclear distances, and approximate results for cross-correlation spectral densities are obtained for complex spin systems, e.g., An1Mn2Xn3....Abstract:
A simple treatment of the dipolar contribution to nuclear magnetic relaxation is developed for molecules in which conformational fluctuations modulate the relevant internuclear distances. Expressions are given for AX system spectral densities using a general model in which conformational fluctuations occur as random jumps among discrete conformations, while the molecule as a whole undergoes rotational diffusion as either a spherical or a symmetric top. Approximations valid for proton spin systems are given for cases in which the jumping rates are either fast or slow compared to rotational diffusion; the results are independent of the jumping rates. Similar results are obtained for cross‐correlation spectral densities. For complex spin systems, e.g., An1Mn2Xn3..., the cross‐relaxation constants σij which couple pairs of magnetizations, depend only upon autocorrelation, spectral densities and are thus easily obtained from the AX system results. Measurement of σij by time resolved Overhauser effect experimen...read more
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Telomeric DNA oligonucleotides form novel intramolecular structures containing guanine-guanine base pairs
TL;DR: Detailed analysis of the hairpin structure formed by the telomeric sequence from Tetrahymena, (T2G4)4, shows that it is a unique structure stabilized by hydrogen bonds and contains G residues in the syn conformation, and it is proposed that this novel form of DNA is important for telomere function and sets a precedent for the biological relevance of non-Watson-Crick base-paired DNA structures.
Journal ArticleDOI
Validation of the 53A6 GROMOS force field.
TL;DR: It was found that the new 53A6 GROMOS parameter set performs as well as the previous parameter sets in terms of protein and DNA stability and that it is better at describing the folding–unfolding balance of the peptide.
Journal ArticleDOI
A theoretical study of distance determinations from NMR. Two-dimensional nuclear overhauser effect spectra
Joe W. Keepers,Thomas L. James +1 more
TL;DR: Theoretical calculations for cross-peak intensities obtained in 2D NOE spectra were calculated for a set of three-proton spins and a setof fourproton spin systems in this article, and the influence of specific types of overall and internal motion on the calculated cross peak intensities and the distances determined from them was tested.
Journal ArticleDOI
NMR investigation of RNA structure
Journal ArticleDOI
Theory of the time dependent transferred nuclear Overhauser effect: Applications to structural analysis of ligand-protein complexes in solution
G.M. Clore,Angela M. Gronenborn +1 more
TL;DR: In this paper, it is shown that the cross-relaxation rates between pairs of bound ligand protons and between a ligand proton and a proton of the protein in the ligand-protein complex can be determined directly and with ease from the initial slopes of the time dependent transferred nuclear Overhauser effect (TRNOE), thus enabling distance ratios between any two such pairs of protons or, if one of the interproton distances is known, interpropton distances to be calculated (on the assumption of a single correlation time for all the corresponding
References
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Journal ArticleDOI
Relaxation Processes in a System of Two Spins
TL;DR: Abragam and Pound's method for the calculation of the longitudinal relaxation time was extended to the transverse relaxation time in this paper, which gave rise to a steady and transient Overhauser effect.
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