Proton-detected 3D N-15/H-1/H-1 isotropic/anisotropic/isotropic chemical shift correlation solid-state NMR at 70 kHz MAS
Chemical shift anisotropy (CSA) tensors offer a wealth of information for structural and dynamics studies of a variety of chemical and biological systems. In particular, CSA of amide protons can provide piercing insights into hydrogen-bonding interactions that vary with the backbone conformation of a protein and dynamics. However, the narrow span of amide proton resonances makes it very difficult to measure H-1 CSAs of proteins even by using the recently proposed 2D H-1/H-1 anisotropic/isotropic chemical shift (CSA/CS) correlation technique. Such difficulties due to overlapping proton resonances can in general be overcome by utilizing the broad span of isotropic chemical shifts of low-gamma nuclei like N-15. In this context, we demonstrate a proton-detected 3D N-15/H-1/H-1 CS/CSA/CS correlation experiment at fast MAS frequency (70 kHz) to measure 1H CSA values of unresolved amide protons of N-acetyl-N-15-L-valyl-N-15-L-leucine (NAVL). (C) 2016 Elsevier Inc. All rights reserved.