Improving Signal Intensities and Assignment of Membrane Proteins by Solid-State MAS-NMR Using Labeled Aromatic Residues

Solid-state magic-angle spinning (MAS)-NMR has rapidly been developing into a structure determination technique for biological macromolecules, as it enables the study of membrane proteins in their native lipid environment, as well as the study of non-soluble or non-crystallizable protein states, such as amyloid fibrils. However, a prerequisite for structure determination is a high level of resonance assignment, which is difficult for many large membrane proteins. This application note discusses the labeling of specific residues of proteins so as to make assignment easier.