Determination of all NOes in 1H–13C–Me-ILV-U−2H–15N Proteins with Two Time-Shared Experiments

We present two time-shared experiments that enable the characterization of all nOes in 1H–13C-ILV methyl-labelled proteins that are otherwise uniformly deuterated and 15N enriched and possibly selectively protonated for distinct residue types. A 3D experiment simultaneously provides the spectra of a 3D NOESY-HN-TROSY and of a 3D NOESY-HC-PEP-HSQC. Thus, nOes from any protons to methyl or amide protons are dispersed with respect to 15N and 13C chemical shifts, respectively. The single 4D experiment presented here yields simultaneously the four 4D experiments HC-HSQC-NOESY-HC-PEP-HSQC, HC-HSQC-NOESY-HN-TROSY, HN-HSQC-NOESY-HN-TROSY and HN-HSQC-NOESY-HC-PEP-HSQC. This allows for the unambiguous determination of all nOes involving amide and methyl protons. The method was applied to a (1H,13C)-ILV−(1H)-FY-(U−2H,15N) sample of a 37 kDa di-domain of the E. coli enterobactin synthetase module EntF.