Heteronuclear single-quantum spectroscopy HSQC

Conformations of mycothiol bimane (MSmB) were studied by H and 13C NMR using rotational nuclear Overhauser effect spectroscopy (ROESY) and heteronuclear single quantum correlation (HSQC) methods with expansions of the anomeric region <2003JOC3380>. NMR characterization of iV-acetyl-L-(Y)-cysteinyl monobimane and peracetylated MSmB was also published (Section 12.10.15.4) <2002JA3492>. 

No general studies have been carried out for these compounds, but there are several reports in which the stereochemistry of the final product has been elucidated by NOESY, correlation spectroscopy (COSY), or heteronuclear single quantum correlation (HSQC) experiments. For example, intensive NOESY experiments were used to establish the exact nature of each of the three cycloadducts 151a-c generated by the cycloaddition of a substituted nitrone to dimethyl (Z)-diethylenedicarboxylate <2000EJ03633>. 

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.

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... 

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... 

HSQC HMQC Heteronuclear single-quantum/multiple-quantum correlation spectroscopy To elucidate structure of organic molecules To determine heteronuclear coupling connectivity... 

Other strategies that show great promise in reducing NMR acquisition time utilise methods to obtain multiple sets of data from one experiment through a concept known as time-shared evolution. An example of this process that should find utility in natural products elucidation was demonstrated by a pulse sequence called CN-HMBC.93 Traditionally, a separate 13C-HMBC and 15N-HMBC were acquired independently. However, the CN-HMBC allows both 13C- and 15N-HMBC spectra to be obtained simultaneously. By acquiring both data sets simultaneously, an effective 50% time reduction can be achieved.93 This approach has also been demonstrated for a sensitivity-enhanced 2D HSQC-TOCSY (heteronuclear multiple bond correlation total correlation spectroscopy) and HSQMBC (heteronuclear single quantum... 

The main emphasis of current carbohydrate structural analysis is the applicability of modern multi-dimensional NMR for solving the two crucial problems in complex carbohydrate structural analysis, namely, the elucidation of the sequence of glycosyl residues and the solution conformation and dynamics of a carbohydrate (150). Techniques include 2D Total Correlation Spectroscopy (TOCSY), Nuclear Overhauser effect spectroscopy (NOESY), rotational nuclear Overhauser effect spectroscopy (ROES Y),hetero-nuclear single quantum coherence (HSQC), heteronuclear multiple quantum correlation (HMQC), heteronuclear multiple bond correlation (HMBC), and (pseudo) 3D and 4D extensions. 

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