The 3D HNCOCG experiment allows the measurement of J(CO-CG) coupling constants in ¹³C,¹⁵N-labeled proteins using the quantitative J-correlation approach.

Implementation on AVANCE spectrometers equipped with a third channel and pulsed field gradients (PFGs).

The original pulse scheme has been reported in 97JB409 and 00JMR126-146 . An alternative 3D H(N)COCG experiment is also proposed to measure such couplings.

The 3D HNCOCG experiment affords a 3D map with (F1,F2,F3=C,N,NH) in which coupling constants are extracted from intensity ratio of the corresponding cross-peak and internal diagonal reference peak.