The 3D (H)CC(CO)NH experiment is specifically designed to correlate the ¹H and ¹⁵N amide resonances of one residue with ¹³CA and all other ¹³C side-chain resonances of its preceding residue via the intervening ¹³CO spin by means of the ¹J(NH), ¹J(N,CO), ¹J(CA,CO) and ¹J(C,C) coupling constants. This experiments is closely related to the 3D CBCA(CO)NH experiment.

Implementation on AVANCE spectrometers equipped with a third channel. Improved versions using pulsed field gradients (PFGs) are also available and, therefore, in such cases gradient technology is required.

The experiment is applied on ¹⁵N,¹³C-labeled proteins. Because the amide (NH) protons are involved, the  (H)CC(CO)NH experiment must be recorded in H₂O.

The 3D (H)CC(CO)NH pulse sequence (  93JMRB114-101 ,   93JB225 ) consisted of the following steps:

1. Initial transfer from ¹H to ¹³C via ¹J(CH) using an INEPT pulse sequence.
2. ¹³C chemical shift evolution during a constant-time t₁ period of duration 1/(4*J(CC)) followed by a ¹³C-¹³C DIPSI-2 pulse train transfers magnetization from all side chain ¹³C resonances to ¹³CA.
3. Fixed evolution delay to achieve antiphase ¹³CA magnetization with respect to ¹³CO via ¹J(CA,CO) followed by  magnetization transfer to ¹³CO by simultaneous 90º ¹³C and ¹³CO pulses.
4. Fixed evolution delay to achieve antiphase ¹³CO magnetization with respect to ¹⁵N via ¹J(N,CO) followed by  magnetization transfer to ¹⁵N by simultaneous 90º ¹⁵N and ¹³CO pulses.
5. ¹⁵N chemical shift evolution during the constant-time t₂ period. Finally, magnetization is transferred back to the NH protons by a retro-INEPT pulse train and proton acquisitionis performed under ¹⁵N decoupling.

This experiment is less sensitive than the CBCA(CO)NH experiment because magnetization is distributed intho the whole spin system. Several modified versions have been proposed incorporating the following modifications:

• A version including WATERGATE:
• A version including 13C-13C cross-polarization transfer but starting from 13C (CC(CO)NH Experiment):
• A version including INEPT transfer but starting from 13C with 1H NOE enhancement: ((H)CCA(CO)NH Experiment):
• A version including INEPT transfer but starting from 13C (CCA(CO)NH Experiment):
• A closely related 3D H(CC)(CO)NH experiment in which proton evolution takes place in the t₁ period.
• Incorporation of PFG and Constant-time periods ( 95JB211) that can be optimized to identify different amino acid spin systems ( 97JB283 ).
• Use of band-selective cross-polarization schemes ( 96JB147).
• Specific versions have been reported for deuterated proteins (  96JB59, 96JB351 and 99JB227 ). In such cases, the initial magnetization can be originated from the 13C spins in an analog 3D CC(CO)NH experiment ( 95JACS4187).
• A 3D TROSY-based version has been proposed for a 2H-labeled membrane protein ( 02JB289)
• A related 3D (H)C(C)NH experiment can be also used to obtain sequential conectivities ( 99JB227)
• In overlapped spectra it could be advisable to record a slightly modified 3D (H)CCCO(N)H experiment ( 99PROG93) :
  
• A 4D HCC(CO)NH experiment has also been proposed (   92FEBS413 and   93JB349 ).

The 3D (H)CC(CO)NH experiment can be recorded in automation mode.

The (H)CC(CO)NH experiment affords a 3D spectrum in which ¹H, ¹⁵N and ¹³C chemical shifts are displayed in three independent dimensions. Sequential connectivities are due to ¹J(NH) +  ¹J(N,CO) +  ¹J(CA,CO) +  n*¹J(C,C).

See list of 3D triple-resonance NMR experiments for doubly-labeled proteins.