Shaping Up Protein NMR

By adapting two techniques from solid-state nuclear magnetic resonance, chemists have found a new way to enhance resolution in protein NMR (J. Am. Chem. Soc., DOI: 10.1021/ja103251h). The method could provide a sharper view of proteins in motion than is now possible with NMR.

Researchers studying protein dynamics by NMR often run into a vexing problem: The very events they wish to study, such as protein folding or ligand binding, can broaden resonances in NMR spectra, sometimes so much that it's hard to extract useful information.

"What one would like to be able to do is narrow the lines when recording the protein NMR spectrum," to get the best resolution and sensitivity possible, says Arthur G. Palmer III of Columbia University. "Then when capturing conformational dynamics," where broadened resonances are useful, "one could turn the broadening back on," he says.

Now, Palmer and postdoctoral researcher Ying Li have done just that. They borrowed a pair of homonuclear dipolar decoupling methods from solid-state NMR and demonstrated the narrowing effect with the protein RNAse A. The technique, which they plan to extend to more proteins, can be combined with other resolution enhancement methods, Palmer notes.

"It will be exciting to see how this method helps in some biologically significant and previously intractable samples," says Lila M. Gierasch, an expert in protein NMR at the University of Massachusetts, Amherst. "Biological function requires dynamics, and this method promises to open the door to systems that refuse to sit still."