Peptide bond conformation in peptides and proteins probed by dipolar coupling-chemical shift tensor correlation solid-state NMR

Multidimensional magic-angle spinning solid-state NMR experiments are described that permit cis and trans peptide bonds in uniformly C-13,N-15-labeled peptides and proteins to be unambiguously distinguished in residue-specific manner by determining the relative orientations of the amide C-13' CSA and H-1-N-15 dipolar coupling tensors. The experiments are demonstrated for model peptides glycylglycine and 2,5-diketopiperazine containing trans and cis peptide bonds, respectively. Subsequently, the measurements are extended to two representative proteins that contain exclusively trans peptide bonds, microcrystalline B3 immunoglobulin domain of protein G and Y145Stop human priori protein amyloid fibrils, to illustrate their applicability to a wide range of protein systems. (C) 2018 Elsevier Inc. All rights reserved.