Fig. 4.
Schematic illustration of reliable cross-peak assignment strategy using 4D C(ali),C(aro)-edited NOESY spectrum. In the top left panel a plane of 4D 13C(ali),13C(aro)-edited NOESY at Tyr 74 Hε/Cε chemical shifts is presented with expanded methyl region of the spectrum on the right side. In the bottom left panel 2D 1H–13C HSQC spectrum is shown with expanded methyl region on the right side. Corresponding cross peaks in the cross-section of 4D spectrum and the methyl region of HSQC are connected by arrows. Relevant methyl-aromatic cross-peaks can be readily assigned (even manually) as the ambiguity is removed by additional aliphatic-13C chemical shift (ω2)