Two-dimensional, nuclear Overhauser

Keepers, J.W. and James, T.L., A theoretical smdy of distance determinations from NMR two-dimensional nuclear Overhauser effect spectra, J. Mag. Resort, 57, 404, 1984. Kemp, W., Organic Spectroscopy, 3rd ed., W.H. Ereeman, New York, 1991. Figueiredo, P. et al., New aspects of anthocyanin complexation intramolecular copigmentation as a means for colour loss Phytochemistry, 41, 301, 1996. 

FIGURE 10. Contour plot of two-dimensional nuclear Overhauser effect ll NMR (NOESY) of the protonated Schiff base of all-traos-retinal, in chloroform, with formate as the counterion. The intermolecular NOE cross-peak observed between H15 of the retinal and the counterion proton, at a mixing time of 0.4 s, is shown. Top trace f2 projection of the 2D NOE spectrum. Reproduced by permission of John Wiley Sons from Reference 36... 

The basis for the determination of solution conformation from NMR data lies in the determination of cross relaxation rates between pairs of protons from cross peak intensities in two-dimensional nuclear Overhauser effect (NOE) experiments. In the event that pairs of protons may be assumed to be rigidly fixed in an isotopically tumbling sphere, a simple inverse sixth power relationship between interproton distances and cross relaxation rates permits the accurate determination of distances. Determination of a sufficient number of interproton distance constraints can lead to the unambiguous determination of solution conformation, as illustrated in the early work of Kuntz, et al. (25). While distance geometry algorithms remain the basis of much structural work done today (1-4), other approaches exist. For instance, those we intend to apply here represent NMR constraints as pseudoenergies for use in molecular dynamics or molecular mechanics programs (5-9). 

Nerdal, W., Pedersen, A.T., and Andersen, 0.M., Two-dimensional nuclear Overhauser enhancement NMR experiments on pelargonidin-3-glucopyranoside, an anthocyanin of low molecular mass, Acta Chem. Scand., 46, 872, 1992. 

Nerdal, W. and Andersen, 0.M., Intermolecular aromatic acid association of an anthocyanin (petanin) evidenced by two-dimensional nuclear Overhauser enhancement nuclear magnetic resonance experiments and distance geometry calculations, Phytochem. Anal, 3, 182, 1992. 

A. Kumar, R. R. Ernst, and K. Wiithrich, Biochem. Biophys. Res. Comm., 95, 1 (1980). A Two-Dimensional Nuclear Overhauser Enhancement (2D NOE) Experiment for the Elucidation of Complete Proton-Proton Cross-Relaxation Networks in Biological Macromolecules. 

Distance Determinations from NMR. Two-Dimensional Nuclear Overhauser Effect Spectra. 

All proton NMR spectra were recorded on a Varian Unity 600 at 25 C. 6 to 10 mg of the disulfide linked c-Myc-Max heterodimeric LZ were dissolved in 0.5 mL of potassium phosphate buffer (50 mM, 10% DiO / 90% H2O and pH 4.7) containing 100 mM KCl and ImM 2,2-dimethyl-2-silapentane-5-sulfonic acid (DSS) to yield solutions ranging from 0.75 to 1.25 mM. Proton resonances were assigned from two-dimensional double quantum filtered correlation spectroscopy (DQF-COSY (21)), two-dimensional total correlation spectrocopy (TOCSY mixing time = 50 ms (22)) and two-dimensional nuclear Overhauser enhancement spectrocopy (NOESY mixing times = 150 and 200 ms (23)) experiments. Sequential assignment of the proton resonances was performed as described by Wuthrich (24). 

A Kumar, RR Ernst, K Wuthrich. A two-dimensional nuclear overhauser enhancement (2D NOE) experiment for the elucidation of complete proton-proton cross-relaxation networks in biological macromolecules. Biochem Biophys Res Commun 95 1-6, 1980. 

MULTAN programs 111). The structure and unit cell packing of each are shown in Fig. 1. Circular dichroism spectra of 10 Cephalotaxus alkaloids have been reported 112). Cephalotaxine was studied by two-dimensional nuclear Overhauser effect correlated spectroscopy (NOESY) 113). 

H-NMR analysis allows the elucidation of GSL structures, without the use of destructive methods and requires small amounts (nmole) of material. In addition to one dimensional 1 H-NMR, other methods such as two-dimensional 1H-NMR shift correlations spectroscopy (COSY), two-dimensional nuclear Overhauser 1 H-NMR spectroscopy (NOESY) and homonuclear two-dimensional spin-echo J-resolved 1 H-NMR spectroscopy. The introduction of1 C-NMR into the field of glycosphingolipid research should give useful information on the stereochemical conformation of molecules. This is of coniderable interest, as they most probably contribute to the immunological specificity of glycosphingolipids (37). 

States DJ, Haberkom RA, Ruben DJ (1982) A two-dimensional nuclear Overhauser experiment with pure absorption phase in four quadrants. J Magn Reson 48 286-292... 

Two-dimensional nuclear Overhauser effect spectroscopy (NOESY) has proven to be a valuable technique in determining the conformations of large polypeptides and oligonucleotides. The slow motional regime in which such molecules lie (where wt> 1) causes the zero quantum transition to be extremely important in determining the rate of cross-relaxation. Crossrelaxation in the homonuclear case is described by the expression ... 

P. D. Thomas, V. J. Basus, and T. L. James, Proc. Natl. Acad. Sci. U.S.A., 88, 1237 (1991). Protein Solution Structure Determination Using Distances from Two-Dimensional Nuclear Overhauser Effect Experiments Effect of Approximations on the Accuracy of Derived Structures. 

Similarly, PPI dendrimers have shifts that are very similar for each repetitive layer, and to completely assign these strac-tures more complex methods such as 2D-NOESY (two-dimensional nuclear Overhauser enhancement spectroscopy) and 3D-NOESY-HSQC (HSQC, heteronuclear single quantum coherence) have been used. These methods will be discussed in the following. ... 

Figure 8 Two-dimensional nuclear Overhauser enhancement spectroscopy NMR spectrum of hGH[6-13] related peptide showing the nuclear Overhauser effect connectivities between a phenylalanine ring (CeHs) and an alanine methyl (CH3) and methine (CH) protons).

The term can usually be evaluated. Consequently, data from one- and two-dimensional nuclear Overhauser spectroscopy studies contribute to the coordination chemists understanding of three-dimensional solution structures and molecular association phenomena such as ion pairs.Distance constraints are usually qualitatively established, based on cross-peak intensities or volumes. Occasionally monitoring the build-up rates is preferred, in order to quantify internuclear distances. ... 

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