The 3D NOESY-HSQC experiment is specifically designed to obtain X-edited NOESY spectra of X-labeled biomolecules and protein-ligand complexes from which homonuclear ¹H-¹H NOEs can be clearly assigned even in overcrowded regions (the mechanism involves ¹H-¹H NOE step followed by an heteronuclear transfer via ¹J(XH)). Similar results can be obtained from an analog 3D NOESY-HMQC experiment.
           

Implementation on AVANCE spectrometers is feasible. Improved versions using pulsed field gradients (PFGs) are also available and, therefore, gradient technology is required. The ¹H-¹³C NOESY-HSQC experiment is usually applied on ¹³C-labeled proteins in D₂0. and the ¹H-¹⁵N NOESY-HSQC experiment is usually applied on ¹⁵N-labeled molecules in H₂0.

The original NOESY-HSQC pulse sequence basically consists of an homonuclear 2D NOESY pulse sequence followed by a ¹H-X HSQC pulse sequence.  However, the HSQC block could be replaced with other schemes: decoupled HSQC, CT-HSQC, PEP-HSQC, HMQC ...(see, for instance, the 3D NOESY-HMQC experiment).

Several improved versions have been proposed incorporating the following modifications:

• 3D NOESY-refocused HSQC experiment ( 95JB433 ).
• Use of PFGs ( 93JMRB317-102 ) combined with solvent suppression using WATERGATE ( 93JMRA241-102 and 95JMRB238-109 ) and PEP methodology ( 95JMRB86-106 ).
• Improved sensitivity using a 45 degree water flip back pulse ( 99JMR451-140 ).
• Incorporation of theTROSY approach ( 99JB77 and 99PNAS9607 ). A 2D [¹H-¹³C]-[¹H-¹³C] NOESY-TROSY experiment for simultaneous detection of backbone NH, aromatic CH and side-chain NH₂ correlations has been reported ( 00JB195 )
• A w1-filtered version has been proposed that uses an double-tuned X-filter element as a initial period ( 96JB492-8 , 97JACS6711 ).
• Simultaneous evolution of ¹³C and ¹⁵N chemical shift in the t₂ period ( 94JMRB197-103 , 94BIO14858 and , 03JB193-27).
• A program called SPIRIT has been developed to simulate 3D NOESY-HSQC experiment ( 98JB17 ).
• Three-way decomposition on 15N-NOESY-HSQC using the software MUNIN ( 02JB191-24 ).
• Increased resolution from a ¹³C-edited NOESY-HSQC experiment with split carbon evolution ( 98JMR191-132 ).
• Related double- and triple-resonance 3D ¹³C/¹⁵N edited NOESY-HSQC ( 94BIO14858 , 95JMRB294-108 , and 95JMRB238-109 ) and 4D ¹³C-¹⁵N-edited NOESY-HSQC experiments have also been proposed ( 90SCI411 ) to observe NOEs between  protons with degenerate chemical shifts.
• The initial NOESY block can be replaced by other homonuclear mixing processes as described in the 3D TOCSY-NOESY-HSQC and NOESY-TOCSY-HSQC experiments ( 92JMR408-96 ).
• A simultaneous 3D NOESY-13C/15N-HSQC has been proposed to determine intra- and intermolecular NOESY in protein ligand complexes ( 01JB107-21 )

The 3D NOESY-HSQC experiment can be recorded in automation mode. More details on practical implementation of the 3D NOESY-HSQC experiment on AVANCE spectrometers can be found in the corresponding Tutorial 3D NOESY-HSQC experiment

The NOESY-HSQC  experiment affords a 3D spectrum in which ¹H, X and ¹H chemical shifts are displayed in three independent dimensions. Thus, the F₁(¹H)-F₃(¹H) plane of a ¹H-¹⁵N NOESY-HSQC spectrum will show a typical 2D F₁(¹H)-F₂(NH) NOESY map. On the other hand, the F₁(¹H)-F₃(¹H) plane of a ¹H-¹³C NOESY-HSQC spectrum will show a typical 2D F₁(¹H)-F₂(¹H aliphatic) NOESY map while the F₁(¹H)-F₂(¹³C) plane will correspond to a conventional 2D ¹H-¹³C HSQC spectrum.

General Reading: 96ENC4733

Simulation of 15N or 13C edited 3D NOESY-HSQC experiment is integrated in the program AURELIA( 99JMR39-137 )