Correlation map

Figure 17. Contour plot of the 360MHz homonuclear spin correlation mpa of 10 (2 mg, CDCL, high-field expansion) with no delay inserted in the pulse sequence shown at the top of the figure. Assignments of cross peaks indicating coupled spins in the E-ring are shown with tljie dotted lines. The corresponding region of the one-dimensional H NMR spectra is provided on the abscissa. The 2-D correlation map is composed of 128 x 512 data point spectra, each composed of 16 transients. A 4-s delay was allowed between each pulse sequence (T ) and t was incremented by 554s. Data was acquired with quadrature phase detection in both dimensions, zero filled in the t dimension, and the final 256 x 256 data was symmetrized. Total time of the experiment was 2.31 h (17).

As in the case of the HN(CO)CA-TROSY scheme, the HN(CO)CANH-TROSY experiment can be readily expanded to a four-dimensional HN(CO)CANH-TROSY experiment without increasing the overall length of the pulse sequence. This can be accomplished by labelling the 13C (f) chemical shift during additional incremented time delay, implemented into the 13C — 13C INEPT delay. As a result, a well-dispersed 13C (i- 1), 13C (i- 1), 15N(i), Hn(0 correlation map is obtained with minimal resonance overlap albeit with the inherent sensitivity loss by a factor of y/2. 

In contrast to the 13C shifts, the 13C resonance frequencies are not indicative of residue type, which makes the assignment more demanding in comparison to the 13C , 15N, Hn correlation map. Nevertheless, the HN(CA)CO-TROSY scheme equipped with the selective 13C refocusing pulses during the 13C -13C/ transfer steps is able to provide 13C (i), 15N(i),... 

The 15N,1H shift correlation maps are most conveniently recorded with a sensitivity-enhanced HSQC sequence with incorporated water flip-back pulses for reduced saturation transfer and pulsed-field gradients for coherence selection. The pulse sequence of the experiment is shown in Fig. 14.4 A. 

Fig. 1. Schematic 2Q (a) and 3Q (b) correlation maps for an ambient AMPX spin system. Direct correlation peaks are denoted with filled circles, while remote peaks are shown with open circles. Full remote dimensions are presented with no aliasing or folding.

Fig. 7. Diagonal or lateral rearrangement followed by symmetrization of the 2Q-HoMQC of cyclosporin A, acquired at 500 MHz in benzene-de at room temperature, (a) Scheme for rearrangement and symmetrization of the full 2Q-HoMQC spectrum. Additional processing may include extraction of a diagonally symmetric correlation map (as shown here) or reverse tilting in order to restore the original arrangement, (b) The same procedure was applied on the real spectrum after DA phasing [11]. Remote peaks and artifacts are both removed from...

Fig. 7. Schematic representation showing how X/Y correlation maps can be obtained either from the appropriate 2D projection of a three-dimensional 1H/X/Y correlation spectrum (a), or alternatively from a sequence of two-dimensional 1H/Y correlations acquired with relayed 1H/(Y)/X coherence transfer via a selected Y-nucleus as relay.

A solution of Cp2TiCl [52] (0.43 g, 2 mmol) in THF was added dropwise to a solution of the epoxide (1.0 mmol) in 20 mL of THF at room temperature. A solution of 1A HC1 in ether (4 mL) was added, and the mixture was stirred for 10 min. The precipitated solid was removed and the filtrate was added to excess (5 mL) of aqueous saturated sodium di-hydrogenphosphate. The organic layer was separated and the aqueous layer was extracted with ether. The product was isolated as a mixture of exo- and endo-Me isomers in 70% yield. The structures were confirmed by l3C-NMR, H-NMR, chemical shift correlation mapping, nOe measurements, and attached proton test (APT) experiments. No [a]D was recorded because the product was isolated as a mixture. 

Fig. 1.7. Two-dimensional Api2-0i2 correlation map for the three-body Coulomb explosion of CS + at a field intensity of 0.2PW/cm2. A logarithmic intensity scale is used to emphasize weak features. The solid curve represents the trajectory obtained from classical mechanical calculations for the sequential explosion pathway. The open circles represent the values for five rotational angles,

Fig. 1.8. The Api2-6 i2 momentum correlation map for the (1,1,1) pathway of CS2 at a field intensity of 0.2PW/cm2, obtained for a all of the coincidence events, b Ekin = 20 1.5eV, c 16 0.5eV, and d 12.5 1.5eV. Solid curves drawn along the vertical and horizontal axes in each map represent the projections of the 2D distribution onto the Api2 and 12 axes, respectively. The 12 distribution expected from the geometry of the neutral CS2 is shown with a dotted line in a...

Fig. 1.9a—d. The pi p>2 correlation maps obtained with a pump pulse only (a), and with At = 300 fs (b), 600 fs (c) and 1 ps (d). Red solid lines indicate results from the free-rotor simulation for the sequential process via the formation of metastable CS2+. The component corresponding to the nuclear wavepacket of CS2+ dissociating towards the symmetric stretching coordinate is visible along the diagonal Pi = P2 line (orange broken circle)... 

FIG. 13.24 Frequency-temperature correlation map for dynamic mechanical, dielectric and NMR measurements on Polyisobutylene. The a and P relaxation regions are shown. Measurements ( ) NMR (O) Dielectric ( ) Mechanical. The full lines are the WLF equation (curved) and the Eyring Equation (straight). From Schlichter (1966). Courtesy John Wiley Sons, Inc. 

FIG. 13.28 Frequency-temperature correlation map for polyfmethyl methacrylate) (PMMA). Dynamic mechanical measurements are indicated by filled points and dielectric measurements by open points ... 

FIG. 13.29 Frequency-temperature correlation map for polystyrene, (o, ) mechanical loss peaks ( , ) dielectric loss peaks (A, ) NMR narrowing and T, (i.e. spin-lattice relaxation time) minima for (open symbols) atactic an (filled symbols) isotactic polystyrenes. From Yano and Wada (1971). Courtesy John Wiley Sons, Inc. 

It should be mentioned that the significance of structural differences can be assessed by means of X-ray crystallography by using local density correlation maps (G. J. Kleywegt, Acta Crystallogr. D Biol. Crystallogr. 1999, 1878-1884). 

R. Freeman and G. A. Morris, Experimental chemical shift correlation maps in nuclear magnetic resonance, /. Chem. Soc. Chem. Commun. (1978), 684-686. 

The first step in the assignment process after considering the chemical shifts themselves is to obtain one or more off-resonance decoupled spectra to determine the number.of protons attached to the carbons and to correlate the carbon and proton resonances. (191, 192) [It remains to be seen whether or not the two-dimensional FT technique of producing chemical shift correlation maps directly (159, 501) will supersede the more conventional methods. ] Only then should more sophisticated experiments be contemplated. Many of the papers concerned with correlation have concentrated on deriving... 

Figure 2. Heteronuclear Single Quantum Correlation Spectra of I N-rCRALBP with and without 11-c/s-retinaldehyde. Results are shown from a gradient-enhanced sensitivity-enhanced heteronuclear single quantum correlation (GESE-HSQC) NMR experiment. The experiment correlates directly bonded pairs in rCRALBP. The correlation map for rCRALBP (29 mg/ml) with bound 11-c/s-retinaidehyde (heavy lines)...

The experiments based on proton detection of rare spin nuclei are usually the most sensitive methods of determining NMR parameters of magnetically diluted spin systems. Unfortunately, recording of 2D correlation maps is usually also a time consuming experiment, especially if wide spectral bands have to be covered in the indirectly detected dimension. The most frequently encountered situation is that only one or a few peaks are expected within a narrow spectral band. However, the position of this band is not known. Several attempts have been made to reduce the experimental time needed to perform such experiments. One approach would be to record a highly truncated data set and use the linear prediction [86,87] to reduce the effect of the data truncation on the appearance of the spectrum. This technique is now available with most... 

Fig. 1. H- - C CT-HSQC spectrum of a sample of 1.5mM Val, Leu, lie (51) methyl-protonated maltose-binding protein (MBP), 2mM /3-cyclodextrin, 20 mM sodium phosphate (pH 7.2), 3mM NaN(, 200pM EDTA, 0. 1 mg/ml Pefabloc, 1 /ig//d pepstatin and 10% D20 recorded at 37°C, on a Varian Unity-1- 500-MHz spectrometer. Acquisition times of 28 and 64 ms were employed (/, t2) along with a relaxation delay of 1.5 s, fora total measuring time of 3 h. (a) Aliphatic region of the H- - C correlation map of MBP, illustrating the selectivity of labelling. Small amounts of residual protonation are observed at the Cy positions of a number of Pro/Arg residues, the Cp positions of Asp and Ser (aliased) residues, and the Cy2 methyl positions of lie. In all cases, intensities of these cross-peaks are less than 10% of the methyl peaks, (b) Methyl region of the H- - C HSQC. Reproduced with permission from Kluwer Academic Publishers Goto et al.H...

Filters which combine measurements of two types of relaxation lead to 2D parameter sets which characterize the evolution of magnetization for each type of relaxation along one axis and correlate both processes. In case of multi-component relaxation such time-domain correlation maps can be analysed for accurate identification of individual components, where discrimination of components is improved by the 2D nature of the available data as compared to the decomposition of ID relaxation curves [Olel, Peel, Wegl],... 

Luo M, Katz L. 2001. Response correlation maps of neurons in the mammalian olfactory bulb. Neuron 32 1165-1179. 

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