The 4D HNCAHA experiment has been designed to trace out many intraresidue and sequential backbone connectivites in large proteins using a single experiment. The same connectivities can be also observed in a 4D HACANH experiment in which the coherence transfer is reversed. Sequential correlations can be unambiguosly identified ina closely related 4D 4D HN(CO)CAHA or HACA(CO)NH experiments

Implementation on AVANCE spectrometers equipped with a triple-resonance probehead is feasible. Improved versions using pulsed field gradients (PFGs) are also available and, therefore, in such cases gradient technology is required. The experiment is recorded on a ¹³C, ¹⁵N-labeled protein in H₂O.

The 4D HNCAHA sequence was described in 92JMR443-98 , 92JB631 , 92JMR444-100 and 94JMRB193-104 .

Related 4D HACANH (or HCANNH) experiment has been also reported ( 92JB631 , 92JACS2262 and 93JMRB223-101 ).

The 4D pulse sequence is a simple extension of the 3D HA(CA)NH and 3D HN(CA)HA experiments and related sequences like 3D (HA)CANH, HACA(N)H, 3D H(N)CAHA, and 3D (H)NCAHA experiments.

Closely related 4D [HAHB][CACB]NH ( 96JACS407 ) and 4D HCCNH pulse sequences have been also published . .

The 4D HNCAHA experiment can be recorded in automation mode.