Transient proton-proton Overhauser effects in horse ferrocytochrome c

Gordon, Sidney L.; Wuethrich, Kurt

doi:10.1021/ja00490a068

Cited by 147 publications

(44 citation statements)

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“…The latter and their similar intensities in particular show that the cyclodextrin must be mobile, otherwise the H(4)±H(6) stilbene protons are too far apart to show NOEs with one type of cyclodextrin proton, given the inverse-dependence of NOE intensity on the sixth power of the distance between interacting protons. [44] This argument is based on the assumption that the axis delineated by the 4-and 4'-carbons of the stilbene is close to parallel to the C6 axis of symmetry of the cyclodextrin. In principle, the NOEs observed, including those between the cyclodextrin C6-H A protons and H(4)±H(6) of the stilbene, could be explained if these axes were substantially out of alignment.…”

Section: Resultsmentioning

confidence: 99%

Separated and Aligned Molecular Fibres in Solid State Self‐Assemblies of Cyclodextrin [2]Rotaxanes

Onagi¹,

Carrozzini²,

Cascarano³

et al. 2003

Chemistry A European J

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The conformations of two [2]rotaxanes, each comprising alpha-cyclodextrin as the rotor, a stilbene as the axle and 2,4,6-trinitrophenyl substituents as the capping groups, have been examined in solution and in the solid state, using (1)H NMR spectroscopy and X-ray crystallography, respectively. In solution, introducing substituents onto the stilbene prevents the cyclodextrin from being localized over one end of the axle. Instead the cyclodextrin moves back and forth along the substituted stilbene. In the solid state, the axles of the rotaxanes form extended molecular fibres that are separated from each other and aligned along a single axis. The molecular fibres are strikingly similar to those formed by the axle component of one of the rotaxanes in the absence of the cyclodextrin, but in the latter case they are neither separated nor all aligned.

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Section: Resultsmentioning

confidence: 99%

Separated and Aligned Molecular Fibres in Solid State Self‐Assemblies of Cyclodextrin [2]Rotaxanes

Onagi¹,

Carrozzini²,

Cascarano³

et al. 2003

Chemistry A European J

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“…For a given correlation time and resonance frequency and a given set of interproton distances calculated from the model, the theoretical NOE values can be calculated from Eq. 1 (2,15).…”

Section: Resultsmentioning

confidence: 99%

Solution conformation of gramicidin S: An intramolecular nuclear Overhauser effect study

Huang

Walter

Glickson

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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The solution conformation of gramicidin S in deuterated dimethyl sulfoxide was investigated by using the intramolecular nuclear Overhauser effect experiment. Experimental Overhauser enhancements were compared with predicted values for each ofthe nine most-stable conformations (M1-M9) calculated by Dygert et al on the basis of energy-minimization procedures [Dygert, M., Go, N. & Scheraga, H. A. (1975) Macromolecules 8,[750][751][752][753][754][755][756][757][758][759][760][761]. By using statistical hypothesis testing, the three lowestenergy conformations (MI, M2, and M3) were shown to give the best fit with the experimental data. All other conformations (M4-M9) were found to be inconsistent with the experimental data.Intramolecular nuclear Overhauser effects (NOEs) are very sensitive to interproton distances when dipole-dipole interaction is the predominant mechanism ofproton relaxation (1). Because of this distance dependence, NOE measurements have been used extensively in conformational studies of small molecules (1); however, their application to peptides is relatively recent (2-7).The cyclic decapeptide antibiotic gramicidin S has been the subject ofmany experimental [ref. 8 perature was 297 ± 1 K. In the NOE experiment, the resonance signal of interest was selectively presaturated for 4 sec before the observation pulse. The decoupler power was set such that the irradiation was highly selective; the decoupler power spillover to the neighboring resonance signals was less than 2% in general, as determined from the difference spectra. For the control spectrum, the irradiation frequency was set away from the spectral region by more than 2 kHz. The degree of saturation of the irradiated lines was 80-90%, and the observed NOEs were finally corrected for 100% saturation of the irradiated peak by dividing by the degree of saturation. One thousand scans were accumulated for each spectrum. To minimize the effects associated with spectrometer drift and to obtain clean difference spectra, the accumulation was alternated every eight scans between the control and the NOE experiments. A 0.5-Hz exponential line broadening was used in Fourier transforming the free induction decays. The NOE difference spectra were obtained by subtracting the control spectrum from the double resonance spectra. The NOE enhancements were calculated as fractional intensity changes for each resonance signal. For overlapping signals and for the C'H2 multiplet of D-phenylalanine, integrated intensities were used in computing the NOEs. RESULTS AND DISCUSSIONThe nuclear Overhauser effect experiment measures the steadystate effect of saturation of a specific spin transition or group of transitions on the intensities of other resonances in the NMR spectrum. The fractional change in the intensity of spin i when a spin s (or a group of such spins) is saturated can be computed by solving a set ofsimultaneous equations of the form (2) oijff(s) + I oyfj(s)where the summation on the right-hand side involves only the saturated spins. The oii and (ri...

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“…Combination of his long-standing experience in NOE spectroscopy with the current state of our work resulted in the 1D transient NOE experiment and the first recordings of NOE buildup curves. 44 Although 1D applications were for technical reasons more limited for transient NOE measurements than for conventional preirradiation techniques, 37 these results had a fundamental impact on our work, not to speak of the fact that the 1D transient NOE experiment contains all the elements of 2D NOESY except for the evolution period (see below). Since transient NOE measurements enabled us to follow the time course of the nonequilibrium magnetization on numerous individually assigned spins in the absence of radiofrequency irradiation, we soon identified the main reason for the success of our 'steady-state' experiments: the preirradiation times had been optimized such that the systems never actually reached the steady state.…”

Section: Studies With Oligopeptidesmentioning

confidence: 96%

“…Experience from more than a decade of NMR with proteins was thus linked with the new technique, which resulted in further rapid progress. The first major steps were to record homonuclear 2D data sets in aqueous solution 99 and to repeat the NOE buildup studies originally performed with the 1D transient NOE experiment 44 with 2D NOESY. 100 The projects were thereafter largely formulated on the basis of needs arising from our daily work with biological molecules, and since contacts with practical life were ensured, new techniques were often in general use in my group within weeks of the discovery.…”

Section: Introducing Multidimensional Nmr To Structural Biologymentioning

confidence: 99%

NMR structures of biological macromolecules

Wüthrich

2003

Magn. Reson. Chem.

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Transient proton-proton Overhauser effects in horse ferrocytochrome c

Cited by 147 publications

References 0 publications

Separated and Aligned Molecular Fibres in Solid State Self‐Assemblies of Cyclodextrin [2]Rotaxanes

Separated and Aligned Molecular Fibres in Solid State Self‐Assemblies of Cyclodextrin [2]Rotaxanes

Solution conformation of gramicidin S: An intramolecular nuclear Overhauser effect study

NMR structures of biological macromolecules

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