A 13C NMR study of the solution dynamics of 1,3,5-triphenylbenzene; analysis of motion about the phenyl-phenyl bond

London, Robert E.; Phillippi, Martin A.

doi:10.1016/0022-2364(81)90154-2

Cited by 7 publications

(4 citation statements)

References 29 publications

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“…The experimental data were therefore fitted to the model described by London 32 for a two-state jump superimposed on overall isotropic motion. This model has successfully been applied to account for differences in relaxation times due to conformational jumps, both in proteins 32 and in organic molecules . The angles used in this model are shown in Figure superimposed on one of the rings of thyroxine, but both rings potentially undergo similar motions, and the angles are defined in the same way.…”

Section: Resultsmentioning

confidence: 99%

“…A number of spectral density functions incorporating internal motion have previously been formulated, ranging from those incorporating internal diffusion of rotatable groups to jump models in which rapid flips occur between defined conformations. [29][30][31][32][33][34][35][36] For any of these models, an examination of the appropriate spectral density functions makes it clear that slow internal motions, i.e., those on the millisecond time scale, do not contribute significantly to T 1 and NOE values. Our previous studies of NMR line shape as a function of temperature 9 have shown that large scale rotations of the outer ring of T4 and T3, which result in interconversion of H2′ and H6′, occur on a millisecond to microsecond time scale.…”

Section: Resultsmentioning

confidence: 99%

“…This model has successfully been applied to account for differences in relaxation times due to conformational jumps, both in proteins 32 and in organic molecules. 33 The angles used in this model are shown in Figure 4 superimposed on one of the rings of thyroxine, but both rings potentially undergo similar motions, and the angles are defined in the same way. In this model, τ o is the overall correlation time, θ is the angle between individual CH vectors and the jump axis, β is the half-angle of the jump, and τ i is the lifetime of individual conformers (hereafter referred to as the internal correlation time to facilitate comparison with other models).…”

Section: Resultsmentioning

confidence: 99%

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H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

Duggan

Craik

1996

J. Med. Chem.

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1H and 13C NMR spin-lattice relaxation times and 13C{1H} nuclear Overhauser enhancement factors have been measured for the thyroid hormones thyroxine, 3,5,3'-triiodothyronine, and 3,5-diiodothyronine, with the aim of determining the internal molecular dynamics in these molecules. Spin-lattice relaxation times of protons on the two aromatic rings of these hormones show remarkable differences, with values for the hydroxyl-bearing ring being a factor of 4-12 times larger than those for the alanyl-bearing ring. This difference is not mirrored in the 13C relaxation times, which are identical within experimental error for the two rings. The 13C data show that the mobility of the two rings is similar, and therefore the difference in proton spin-lattice relaxation times arises because the protons of the alanyl-bearing ring are efficiently relaxed by interactions with neighboring protons on the side chain. Quantitative analysis of the 13C relaxation data shows that there must be a significant degree of internal flexibility in the thyroid hormone molecules. The NMR data suggest that in methanol the molecules tumble with an overall correlation time of approximately 0.35 ns, but that rapid internal motion (in the form of jumps between two stable conformations) occurs on a 30-fold faster time scale. When combined with previous variable temperature NMR studies that show interconversion between proximal and distal forms of the outer ring on the microsecond time scale, the results provide a complete description of the conformations and both fast and slow internal motions in the thyroid hormones. The findings suggest that modeling studies of thyroid hormone interactions with receptor proteins should take into account the possibility that these internal motions are present. In effect, the thyroid hormones may likely populate a larger range of conformations in the bound state than might be inferred from just the lowest energy forms seen in the crystal and solution states.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

Duggan

Craik

1996

J. Med. Chem.

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“…The experimental data were therefore also analyzed using the model-free approach of Lipari and Szabo. 26 A segment of the system (the square) instantaneously jumps between the two states defined by the angles <p from the plane about which the jumps occur. The plane has an angle 9 between itself and the Z-axis.…”

Section: Resultsmentioning

confidence: 99%

13C NMR Relaxation Study of Molecular Motion in the DNA-Binding Ligand Hoechst 33258

Embrey¹,

Craik²

1995

J. Phys. Chem.

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I3C spin-lattice relaxation times (TI) and nuclear Overhauser enhancement (NOE) factors have been measured at three magnetic field strengths (corresponding to resonance frequencies of 22.5, 75, and 100 MHz) for the DNA-binding ligand Hoechst 33258. This molecule comprises two benzimidazole moieties, an Nmethylpiperazine ring and a phenol ring, and adopts an anisotropic curved shape that assists in its binding to the minor groove of DNA. The I3C relaxation data were interpreted in terms of various models for molecular motion. It was determined that in solution the molecule tumbles anisotropically and that there is a significant degree of internal motion associated with both the phenol and piperazine moieties. Models which involve the rapid jumping of C-H moieties between conformational states provided a good fit to the relaxation data, as did the model-free approach of Lipari and Szabo (J. Am. Chem. SOC. 1982, 104, 4546).

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A critical evaluation of models for complex molecular dynamics: Application to NMR studies of double‐ and single‐stranded DNA

et al. 1983

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SynopsisThe nature of internal and overall motions in native (double-stranded) and denatured (single-stranded) DNA fragments 120-160 base pairs (bp) long is examined by moleculardynamics modeling using 13C-nmr spin-relaxation data obtained over the frequency range of 37-125 MHz. The broad range of I3C frequencies is required to differentiate among various models. Relatively narrow linewidths, large nuclear Overhauser enhancements (NOES), and short T1 values all vary significantly with frequency and indicate the presence of rapid, restricted internal motions on the nanosecond time scale. For double-stranded DNA monomer fragments (147 bp, 24 8, diam a t 32"C), the overall motion is that of an axially symmetric cylinder ( r x = -lop6 s; 7, = -1.8 X s), which is in good agreement with values calculated from hydrodynamic theory ( T~ = -1.8 X s). The DNA internal motion can be modeled as restricted amplitude internal diffusion of individual C-H vectors of deoxyribose methine carbons Cl', C3', and C4', either with conic boundary conditions (7, = -4 X 10-9 s, Ocone = -21O) or as a bistable jump ( T A = T B = -2 X s, O = -15"). We discuss the critical role in molecular-dynamics modeling played by the angle (p) that individual C-H vectors make with the long axis of the DNA helix. Eeat denaturation brings about increases in both the rute and amplitude of the internal motion (described by the wobble model with rW = -0.2 X s, O,,,, = -50' 1, and overall motion is affected by becoming essentially isotropic ( T~ = T~ = -5 X s) for the single-stranded molecules. Since '3C-nmr data obtained at various DNA concentrations for C2' of the deoxyribose ring is not described weli by the above models, a new model incorporating an additional internal motion is proposed to take into account the rapid, extensive, and weakly coupled motion of C2'. s; T~ = -2.7 X

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A 13C NMR study of the solution dynamics of 1,3,5-triphenylbenzene; analysis of motion about the phenyl-phenyl bond

Cited by 7 publications

References 29 publications

H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

13C NMR Relaxation Study of Molecular Motion in the DNA-Binding Ligand Hoechst 33258

A critical evaluation of models for complex molecular dynamics: Application to NMR studies of double‐ and single‐stranded DNA

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A 13C NMR study of the solution dynamics of 1,3,5-triphenylbenzene; analysis of motion about the phenyl-phenyl bond

Cited by 7 publications

References 29 publications

H and 13C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

H and 13C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

13C NMR Relaxation Study of Molecular Motion in the DNA-Binding Ligand Hoechst 33258

A critical evaluation of models for complex molecular dynamics: Application to NMR studies of double‐ and single‐stranded DNA

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Product

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H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine

H and ¹³C NMR Relaxation Studies of Molecular Dynamics of the Thyroid Hormones Thyroxine, 3,5,3‘-Triiodothyronine, and 3,5-Diiodothyronine