Identification of spin diffusion pathways in proteins by isotope-assisted NMR cross- relaxation network editing

A new isotope-assisted cross-relaxation editing experiment, 1H-13C]DINE-NOESY1H-15N]HSQC (DINE = Double INEPT Edited), is proposed. It is based on the selectiveinversion of CH/CH3 or CH2 protons in the middle of the mixing time. The experiment sortsout the spin diffusion paths according to the principal mediators, either the CH/CH3 or theCH2 protons. This is useful in the structure refinement process, as it enables proper alignmentof the aliphatic protons in the vicinity of NH protons.