Transfer NOESY

Moseley, H. N. B., Curto, E. V., Krishna, N. R. Complete Relaxation and Conformational Exchange Matrix (CORCEMA) analysis of NOESY spectra of interacting systems two-dimensional transferred NOESY. J. Magn. Reson. Sen B 1995, 108, 243-261. 

Fig. 7.27 a Transferred NOESY, b cross and c reference traces from the transferred rcCH CH-HCCH experiment that display the dependence of the rate of the transferred cross-correlated relaxation... 

The basic theoretical formulation for the quantitative analysis of the STD-NMR data is similar to the one we developed for the analysis of transferred NOESY data, and is based on a complete relaxation and conformational exchange matrix (CORCEMA) theory [33]. 

The ID TOCSY module has been used in many pseudo-3D experiments (or alternatively referred to as ID analogues of 3D experiments in the literature) such as ID TOCSY-NOESY or ID TOCSY-ROESY experiments. The TOCSY part of these experiments are similar to that of a regular ID TOCSY where a selective excitation of a desired signal is followed by a MLEV17-type isotropic mixing. The second polarization transfer (NOESY or ROESY) step can either be non-selective [29, 59-61] or selective [62-65]. 

GMPCPP. While the EpoA and DDM experiments report on the early events of ligand binding to nonpolymerized tubulin, the peloruside A experiments report on its association to polymerized MT. Transferred NOESY data were analyzed quantitatively following the FRM approach and were consistent with the B conformation. The binding epitope of peloruside A was deduced from STD experiments, that with short saturation times (<500 ms) displayed signal enhancements of protons H2, H8, H17, H19-H24, and the three methoxy rings. 

Spectra of 10 mM samples of desmopressin were recorded in the absence and presence of 1.0 mM NP-II. Transferred NOESY and NOESY experiments were recorded at 150 ms and 300 ms, respectively. The spectral width were 6000 Hz in both dimensions with 1024 complex points in t2 dimension with 512 FIDs in the tl dimension. 

Two specific relaxation approaches are discussed the first approach involves measurement of the NMR longitudinal and transverse relaxation times (Ti and T2) wheareas the second approach involves measurement of transferred NOE intensities. In the relaxation time measurement approach, the distance information is assumed known and the focus is on dynamic information. In the transferred NOESY approach, the motion is considered constant and the focus is on the structural information. These are discussed in terms of two different biological systems. 

Figure 2. Transferred NOESY and NOESY spectra of desmopressin. The aromatic-sidechain region of the transferred NOESY spectrum of desmopressin in the presence of 0.1 mole equivalent NP-II (panel A) and the same spectral region of the NOESY spectrum of desmopressin in absence of NP-II (panel B).

Fig. 49. Determination of the structure of Ant-Ado (d) in the complex with EF-Tu. a) The transfer NOESY experiment is shown with the cross-peaks between H8 of adenine and the sugar protons, b) shows the titration of the cross-peaks originating from cross-correlated relaxation between C3,H3 and C4,H4 vectors with increasing concentration of the protein, c) The reference peak, e) The conformation of the molecule in the protein.

Analysis of NOESY Spectra of Reversibly Forming Ligand-Receptor Complexes Application to Transferred NOESY... 

Figure 3. Schematic representation of the transfer NOESY (trNOESY) experiment. Ligands have to sample the binding site of the protein (shown in red) often enough during the mixing time in order to generate a transfer of NOEs. It follows that dissociation of the protein-carbohydrate complex must be fast on the relaxation time scale. With mixing times tn, usually being 50-300 ms for trNOESY experiments, dissociation rates of ca. 50-100 Hz are sufficient.

Figure 1.45 Coherence transfer pathways in 2D NMR experiments. (A) Pathways in homonuclear 2D correlation spectroscopy. The first 90° pulse excites singlequantum coherence of order p= . The second mixing pulse of angle /3 converts the coherence into detectable magnetization (p= —1). (Bra) Coherence transfer pathways in NOESY/2D exchange spectroscopy (B b) relayed COSY (B c) doublequantum spectroscopy (B d) 2D COSY with double-quantum filter (t = 0). The pathways shown in (B a,b, and d) involve a fixed mixing interval (t ). (Reprinted from G. Bodenhausen et al, J. Magn. Resonance, 58, 370, copyright 1984, Rights and Permission Department, Academic Press Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887.)...

Both homonuclear and heteronuclear versions of relayed nOe experiments are known. The homonuclear relayed NOESY experiment involves both an incoherent transfer of magnetization between two spins H and H/ that are not coupled but close in space, and a coherent transfer of magnetization between two spins H(and H that are /-coupled together. The magnetization pathway may be depicted as... 

The NMR techniques discussed so far provide information about proton-proton interactions (e.g., COSY, NOESY, SECSY, 2D y-resolved), or they allow the correlation of protons with carbons or other hetero atoms (e.g., hetero COSY, COLOC, hetero /resolved). The resulting information is very useful for structure elucidation, but it does not reveal the carbon framework of the organic molecule directly. One interesting 2D NMR experiment, INADEQUATE (Incredible Natural Abundance Double Quantum Transfer Experiment), allows the entire carbon skeleton to be deduced directly via the measurement of C- C couplings. 

Oil and 0)2, and (b) 2D shift-correlation spectra, involving either coherent transfer of magnetization [e.g., COSY (Aue et al, 1976), hetero-COSY (Maudsley and Ernst, 1977), relayed COSY (Eich et al, 1982), TOCSY (Braunschweiler and Ernst, 1983), 2D multiple-quantum spectra (Braun-schweiler et al, 1983), etc.] or incoherent transfer of magnedzation (Kumar et al, 1980 Machura and Ernst, 1980 Bothner-By et al, 1984) [e.g., 2D crossrelaxation experiments, such as NOESY, ROESY, 2D chemical-exchange spectroscopy (EXSY) (Jeener et al, 1979 Meier and Ernst, 1979), and 2D spin-diffusion spectroscopy (Caravatti et al, 1985) ]. 

A 3D spectrum of a three-spin subsystem in which all the nuclei are coupled to one another, such as C(H/i)(Hb)-C(Hc), will lead to 27 peaks, comprising six cross-peaks, 12 cross-diagonal peaks (six at o) — o>2 and the other six at 0)2 = (O3), six back-transfer peaks, and three diagonal peaks. However, in the case of a linear three-spin network (e.g., CH -CHg-CHc), the number of peaks will depend on whether two equal (e.g., COSY-COSY or NOESY-NOESY) or unequal (e.g., COSY-NOESY) mixing processes are... 

In the case of a COSY-NOESY spectrum having an unequal mixing, let us consider two nuclei (say, A and B) that are spatially close but belong to different coupling networks, and nuclei B and C, which have scalar coupling with each other but are spatially distant. The only transfers allowed in this situation are ... 

The pulse sequences for HMQC-COSY and HMQC-NOESY experiments are presented in Fig. 6.10. The 3D HMQC-COSY spectrum of a N labeled tripeptide is shown in Fig. 6.11. Since the coherence transfer involved in this experiment is N([Pg.362]

Two-dimensional relayed NOESY experiments (Wagner, 1984 Kessler et al., 1988) give cross-peaks that could be a superposition of nOe s resulting from different relay nuclei. This complicates the extracting of crossrelaxation rates. The 1D NOESY experiment (Kessler et al., 1989a), however, allows the path of the magnetization transfer to be clarified. 

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.

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