Web Date: April 18, 2007
Faster Route To NMR Values
A new technique makes it easier and faster to determine a type of fundamental nuclear magnetic resonance (NMR) spectroscopy value that is rich with information about molecules. Known as chemical shift anisotropy (CSA) tensors, these values previously have been difficult to obtain.
CSA tensors measure variations in NMR chemical shift that occur when a functional group in a protein or other compound changes orientation with respect to a fixed magnetic field. Chemists use CSA data to refine protein structures, elucidate enzyme mechanisms, and validate theoretical calculations of atomic properties. Traditionally, researchers could measure only one CSA tensor at a time, and recent advanced techniques boosted this to about 10 tensors per experiment.??
Now, Chad M. Rienstra and coworkers at the University of Illinois, Urbana-Champaign, have devised a way to obtain about 100 CSA tensors at a time, approximately an order-of-magnitude improvement (J. Am. Chem. Soc., DOI: 10.1021/ja0701199). They report using the technique to determine about 95% of the CSA tensors in a small protein and have since achieved similar results with larger proteins.??
Robert Tycko of the Laboratory of Chemical Physics at the National Institute of Diabetes & Digestive & Kidney Diseases comments that CSA tensor values are "a rich source of information about molecular structure and dynamics." A key benefit of the new work, he notes, is its ability to provide "a database of tensor values for residues in various secondary structures, which can then be used in structural studies."
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