Heteronuclear single quantum spectrum

FIGURE 2.1 heteronuclear single-quantum coherence spectrum of 5-carboxypyranocyanidin... 

Record the 2-D H-13C heteronuclear single quantum coherence (HSQC) spectrum (Braun et al., 1998, pp. 497-500). 

NMR) studies. The protein was mostly recovered in soluble form (see Fig. 6, lanes T, S of At03). To probe its folding state, heteronuclear single-quantum coherence (HSQC) with 157V-labeled FT protein (four amino acids—Gly, Ala, Leu, and Gin, replaced with 157V-labeled versions) was measured by NMR. The distribution of resonances in the 2D 15/V-XH correlation spectrum shows a reasonable number of signals and indicates that the protein is folded in solution... 

Fig. 8. Heteronuclear single-quantum coherenc (HSQC) spectrum of the hypothetical protein of the flowering locus T protein produced in the cell-free system. The FT protein was synthesized in the same way as in Fig. 6 except that Ala, Leu, Gly, and Gin in both translation and substrate mixture were replaced with their -labeled forms (Isotec, Inc ). After incubation for 48 h, the reaction mixture (1 mL) was dialyzed against 10 mMphosphate buffer (pH 6.5) overnight, and then centrifuged at 30,000g for 10 min. The supernatant containing 30 xMof the protein was directly subjected to nuclear magnetic resonance spectroscopy. The spectrum was recorded on a Broker DMX-500 spectrometer at 25°C, and 2048 scans were averaged for the final H- WHSQC spectrum.

Fig. 6. H- SN heteronuclear single-quantum coherence (HSQC) spectrum of yeast ubiquitin overexpressed mEscherichia coli cells and purified (1.0mA/, 128 [tl] 1024 [t2] complex points, 64 scans), obtained at the H resonance frequency of 500 MHz. Spectral widths are 1600 and 6250 Hz in Ft and F2, respectively.

FIGURE 12.9 Example of heteronuclear single quantum coherence (HSQC) applied to allylbutyl ether (300 MHz).The correlations of H and 1 C chemical shifts are clearly shown. Note the similarity to Fig. 10.10, which displays a HETCOR spectrum. For a sample of this sort, where signal/noise ratio is no problem, there is little to choose between the two techniques, but HSQC is inherently much more sensitive. 

Introducing a heteronuclear dimension reduces the signal overlap by using the additional chemical shift dispersion of the heteronuclei and facilitates assignment of biomolecules. The Heteronuclear Single Quantum Correlation (HSQC) experiment yields a spectmm that correlates the chemical shift of a spin with that of a covalently bound or spin (55). In a HSQC spectrum, every peak represents the correlation of an amide bond, which shows correlations... 

A simple way of illustrating multidimensional NMR is through reference to hetero-nuclear correlation spectroscopy, in which two or more separate frequency dimensions are correlated with one another. For example, a particularly valuable 2D experiment is heteronuclear single quantum correlation (HSQC) spectroscopy, in which the resultant spectrum has two frequency axes, corresponding to and frequency dimensions, and one intensity axis. Analogous HSQC... 

The 3EI NMR spectrum of (7) at low temperatures shows the presence of two diastereoisomers.35 Ab initio calculations have been made of 15N chemical shift differences induced by Ca2+ binding to EF-hand proteins.36 111 and 13 C NMR spectra were used to characterise calcium pyrrolates, [Ca (2-dimethylamino-methyl)pyrrolyl 2(D)n], where D = thf, py, n = 2, D = dmf, TMEDA, n = l.37 The 3H NMR spectra of (ri5-Gaz)M(thf)2, where M = Ca or Yb, and (r 5-Gaz)Yb(py)2, where Gaz = l,4-dimethyl-7-isopropylazulene, show exclusive formation of N2-ara, z-metallocenes.38 - N heteronuclear single quantum coherence spectra were used to study and compare the binding of Ca2+ and La3+ to calmodulin and a calmodulin-binding peptide.39... 

The final step in the assignment of all resonances is correlating the C peaks with the proton peaks. This can often be done from chemical shift alone for the anomeric resonances, but not for other ring atoms. The most important pulse sequence here is HSQC (Heteronuclear Single Quantum Correlation), which involves six pulses to protons and four to C. The spectrum is now a non-symmetrical map with a peak at each carbon attached to a proton the projection on the C axis is the C DEPT spectrum and on the proton axis the ordinary proton spectrum (Figure 4.18). 

Further 2-D H total correlation spectroscopy (TOCSY) anal3rsis of fire humate from the cellulose treatment indicates that this region is rich in aCH and CH2 of amino acid residues phis CH/CH2 of polysaccharides (Figure 6). These assignments were made based on the proton covalent connectivity and chemical shift information acquired from the TOCSY spectrum, and are in agreement with the 2-D heteronuclear single quantum coherence (HSQC) analysis... 

Figure 21.9 is a two-dimensional heteronuclear single quantum coherence (HSQC) spectrum of the protein. This is an NMR spectrum that shows H-N pairs in the protein (hydrogen along the horizontal axis and nitrogen on the vertical axis). There is one N-H per amino acid, so there is one peak per amino acid residue (numbered in the spectrum). Some of the side chains of the amino acid residue also contain N-H pairs. 

Figure 21.9 Two-dimensional heteronuclear single quantum coherence (HSQC) spectrum of the protein LysM (supplied by Professor Michael Williamson, University of Sheffield)... 

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