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The 2D HSQC-NOESY experiment is an hybrid inverse experiment consisting of an initial HSQC pulse train followed by a NOESY building block. In the first step, magnetization is transferred from the X nucleus (13C or 15N) to the directly-bonded proton nuclei via 1J(CH). In the second step, polarization transfer is achieved via dipolar coupling (NOE). Similar results are obtained from the analog 2D HMQC-NOESY experiment.REQUIREMENTS
Easy implementation on any AVANCE spectrometer equipped with an inverse probehead.VERSIONS
The basic sequence of the 2D HSQC-NOESY experiment is based on the 2D HSQC experiment in which a NOESY mixing sequence (consisting of 90º(1H)-delay-90º(1H)) is inserted prior to acquisition ( 90JMR488-87 and 92JMR575-100 ). Carbon decoupling is optionally applied during proton acquisition.EXPERIMENTAL DETAILSImproved results can be obtained from the gradient enhanced version (see ge-2D HSQC-NOESY experiment).
Related 2D HSQC-TOCSY-NOESY and HSQC-NOESY-TOCSY experiments have been also proposed ( 92JMR174-96 ) .
Some applications: 93JMRB240-101
The 2D HSQC-NOESY experiment can be recorded in routine/automation modes. The experiment is basically optimized as described for the 2D HSQC experiment. The most important parameter to optimize is the NOESY mixing time length.SPECTRAMore details on practical implementation of 2D HSQC-NOESY experiments on AVANCE spectrometers can be found in
Tutorials: 2D inverse experiments Tutorials: 2D gradient-based inverse experiments
The HSQC-NOESY spectrum correlates chemical shifts of heteronucleus X (F1 dimension) and protons (F2 dimension) via the direct heteronuclear coupling 1J(XH). Two different cross-peaks are present for each X resonance: The direct 1H-X NOE connectivites and the NOE 1H-X connectivities due to the cumulative transfer 1J(XH) + 1H-1H NOE. The same NOE effects could also be detected by a 2D HMQC-ROESY, 2D HSQC-ROESY and 2D HSQC-ROESY experiments.RELATED TOPICS
Comparison of different 2D inverse correlations have been carried out ( 90JMR488-87 ).A 3D HSQC-NOESY experiment is easily designed by incorporating a second variable evolution period between the HMQC and the NOESY mixing period. On the other hand, a very similar pulse sequence is used for the w1-X-filtered 2D NOESY experiment by fixing the variable period in the HSQC block of this 3D HSQC-NOESY experiment.
Related experiments:
2D Inverse experiments 2D Inverse gradient-enhanced experiments
