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Biomolecular NMR

Sparse Labeling for Protein NMR

[2,3-13C]-Labeled Aromatic Residues as a Means to Improving Signal Intensities and Kick-Starting the Assignments (Application Note 22)

Matthias Hiller, et al.
Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Strasse 10, 13125 Berlin, Germany

  • [2,3-13C]-Labeled Aromatic Residues as a Means to Improving Signal Intensities and Kick-Starting the Assignments (Application Note 22)

It is standard practice to enrich proteins to high levels of 13C enrichment in-order to make spectral assignments and to ultimately determine structure.  However, a high level of uniform 13C enrichment creates scalar and dipolar coupling between the directly bonded 13C nuclei, which for dipolar-based sequences used in solid state NMR, creates large signals which often obscures low-intensity, information-rich signals produced from long range coupling.  For scalar-based sequences used in solution state NMR, the presence of directly bonded 13C nuclei will degrade spectral resolution and provides an unwanted dipolar relaxation mechanism for the alpha carbon.

Reduction of 13C-13C dipolar coupling is made possible by sparse 13C labeling.  13C sparse labeling is where the expressed protein does not contain adjacent 13C nuclei.  This can be accomplished to a large degree by using selectively 13C labeled carbon sources for the protein expression. There are several different substrates available for 13C sparse labeling, including glucose, glycerol and pyruvate.


Kevin Millis, PhD

Kevin Millis, PhD

Senior Scientist, Application Development Manager

Kevin Millis, PhD, is the Senior Scientist and Market Development Manager for all NMR and mass spectrometry product lines. Kevin is responsible for Technical Services both internally and externally for all CIL customers as well as being responsible for the application and market development for the CIL products.