Table 1.

The summary of NOE constraints derived from standard 3D ¹³C-edited NOESY HSQC (tuned to aromatic carbons) and 4D ¹³C(ali),¹³C(aro)-edited NOESY

	3D 13C(aro)-edited NOESY HSQC	4D 13C(ali),13C(aro)-edited NOESY	Number of common constraints from 3D and 4D spectra
Constraints between aromatic and aliphatic protons	156	131	111
Intraresidual (i − j ≤ 1)	63	50	44
Medium range (1 < i − j < 5)	22	14	10
Long range (i − j ≥ 5)	45	44	37
Intersubunit	26	23	20

4D spectrum provided 20 additional constraints that could not be assigned in the 3D spectrum. A number of weak NOE contacts present in 3D spectrum were not detected in 4D NOESY, including mostly intraresidual Hα–Hδ, Hα–Hε and Hβ–Hε NOE contacts. Nevertheless, the number of most relevant long range and intersubunit constraints remained virtually equal