Heteronuclear single quantum correlation HSQC spectra

Target-based detection methods, mainly using heteronuclear single-quantum correlation (HSQC) spectra of or... 

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... 

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... 

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. 

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... 

HMQC (heteronuclear multiple quantum correlation) is a variant of the HSQC spectrum that gives essentially the same results with a slightly different strategy (Fig. B. 14). Instead of converting antiphase SQC into antiphase 13C SQC, a single 90° pulse on 13C alone converts it into multiple quantum coherence (DQC and ZQC). DQC (I+S+) is selected... 

Figure 15 (A) The basic HSQC (heteronuclear single quantum coherence) pulse sequence. (B) The HSQC spectrum of the aliphatic region of [1] with the C along and the H spectrum along f2- The C- H connectivities are marked for the same molecular fragment as in Figure 14. Other sequences of proto-nated carbons can be determined from the same spectrum while an />bond (n=2,3) C- H shift correlation spectrum such as HMBC, COLOC or FLOCK (see Table 2) can identify non-proto-nated carbons and tie together the molecular fragments into a complete structure.

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