2D NOESY

Figure 6.3 Schematic representation of the resolution advantages of 3D NMR spectroscopy, (a) Both pairs of protons have the same resonance frequency, (b) Due to the same resonance frequency, both pairs exhibit overlapping crosspeaks in the 2D NOESY spectrum, (c) When the frequency of the carbon atoms is plotted as the third dimension, the problem of overlapping is solved, since their resonance frequencies are different. The NOESY cross-peaks are thus distributed in different planes.

From the complete ensembles of conformations found by the CICADA analysis of the pentasaccharide, H- H distances have been calculated.These distances (not shown here) can be compared to the interesidual H- H distances estimated from the NOE build-up rates of the corresponding cross-peaks in the 2D NOESY spectra, to be made un future experiments. 

The oldest and most widely used structural restraints in NMR spectroscopy are distance restraints derived from NOE experiments [1]. Transient NOE, 2D NOESY and ROESY spectra provide valuable information for interatomic distances up to 5 A that will be discussed in the following. 

Fig. 9.1 The internuclear transfer of magnetization via NOE cross-relaxation in an isolated spin-pair. (A) Build-up curves for the cross-peak intensity in a 2D NOESY experiment for various internuclear distances r. The dashed line indicates a typical mixing time tm = 300rns used for drug-like molecules.

Fig. 9.2 Schematic representation of the three basic experiments useful for the determination of (A) transient NOE experiment, (B) 2D NOESY and (C) 2D ROESY. The gray-filled half-circle represents a frequency-selective inversion pulse which inverts the spin to which the cross-relaxation...

The DNA binding of [cp Ir(dppz)(Aa)]"+, dppz = dipyrido[3,2-a 2, 3 -c]phenazine, Aa = S-coor-dinated amino acid or peptide, has been investigated by UV-vis spectroscopy, 2D-NOESY, and gel electrophoresis. The complexes intercalate into DNA adjacent to T2 from the major groove. The X-ray structural data for [cp IrCl(dppz)](CF3S03)4 and [ cp Ir(9-EtG)(Phen)](CF3S03)2, where GH = guanine, are reported.423... 

We shall use compound 3 to demonstrate the results obtained from a 2D NOESY experiment, and for comparison we shall use the COSY spectrum obtained from the same compound. Figure 25 shows the COSY (a) and 2D NOESY (b) spectra of compound 3. 

The 2D NOESY spectrum of the Schiff base being a derivative of histidine ethyl ester and 3-hydroxypyridin-4-carboxaldehyde has shown that in THF-d8 solution the E conformation of the molecule is preferred.22... 

The polyrotaxane fraction was insoluble in water and DMF, but soluble in DMSO and 0.1 N NaOH. Its XH NMR spectrum- shown in Fig. 47, together with those for the second and third fraction- indicates that the polyrotaxane consists of CD, PEG-BA, and dinitrophenyl groups and that all peaks are broadened by complexation, which implies that a-CD rings become less mobile when including PEG. 2D NOESY NMR spectra showed that the H-3 and H-5... 

Fig. 10.11. 2D NOESY data of astemizole (5). The mixed phase correlations in the aromatic region (boxed) are examples of the artifacts described in the text.

Combining 2D-NOESY and 2D-ROESY NMR experiments with molecular modelling protocols, Kuhn and Kunz32 have been able to study the saccharide-induced peptide conformational behaviour of the recognition region of Ll-Cadherin. The detailed conformational analysis of this key biomolecule not only proves that the saccharide side chain exerts a marked influence on the conformation of the peptide chain, but also that the size and type of the saccharide indeed strongly affects the conformation of the main chain. 

In the transferred NOE (trNOE) experiment, a ID or 2D NOESY experiment is recorded [31]. The intermolecular NOE build-up to be used as a parameter in Eq. (5) arises from the bound state but is observed via the free ligand, requiring rapid exchange between bound and free states. The technique is described in more detail in Chapt. 16. 

As expected, the performance of this filter over the whole 13C shift range surpasses that of a conventional single or even double filter. The authors have successfully applied this technique to a 2D NOESY spectrum with 13C-filtering in both dimensions, acquired on the 26 kDA complex between a [U-13C,15N]-labeled DNA-binding protein domain and a 15-mer DNA ligand (unlabeled) [24]. 

Fig. 17.7 2D NOESY experiment with 13C, 15N fil- The sequence uses double filters for 13C, single ter in both H dimensions, selecting intramolecu- filters for 15N, and additional 13C, 15N purge lar NOEs within the unlabeled components [22]. pulses during the NOE mixing time ( ).

More recent applications comprise, for example, the identification of the binding site of 18 kDa human cardiac troponin C for the drug bepridil [36]. For this study, the unlabeled ligands were bound to selectively [13CH3-Met, Phe-d8]-labeled protein (Fig. 17.8). First, the 13CH3-Met signals of troponin C were easily identified from 13C-HSQC spectra. In a 2D NOESY spectrum with 13C-editing in one dimension, intermolecular NOEs could... 

Various studies were focusing on the conformational behavior of the cinchonan carbamate selectors in free and complexed form, which could readily be derived from the dihedral coupling constant of the Hs-Hg protons ( /hsh9) and intramolecular NOEs as measured by 2D-NOESY [92,93] or two-dimensional rotating frame Overhauser effect spectroscopy (2D-ROESY) [65] spectra. 

This review describes experimental techniques, then gives some selected results of H, and NMR studies of pressure effects on the structure, dynamics and phase transitions of phospholipid bilayers. Other examples deal with 2D-NOESY experiments on lipid vesicles and pressure effects on the interaction of anaesthetics with phospholipid bilayers. Furthermore, we discuss... 

In order to provide quantitative information on the elfeets of pressure on eross-peak intensities, we earned out 2D-NOESY experiments on pure POPC (l-palmitoyl-2-oleoyl-x -glyeero-3-phosphatidylcholine (Ci6 o, Cig c )) and DMPC (l,2-dimyristoyl-OT-glyeero-3-phosphatidylcholine (di-Ci4 o)) lipid bilayers.As an example, we present data on POPC, a phospholipid which is also a very important eomponent of animal cell membranes. It has an... 

---