Mixed pyruvate labeling enables backbone resonance assignment of large proteins using a single experiment

Nat Commun. 2018 Jan 24;9(1):356. doi: 10.1038/s41467-017-02767-8.


Backbone resonance assignment is a critical first step in the investigation of proteins by NMR. This is traditionally achieved with a standard set of experiments, most of which are not optimal for large proteins. Of these, HNCA is the most sensitive experiment that provides sequential correlations. However, this experiment suffers from chemical shift degeneracy problems during the assignment procedure. We present a strategy that increases the effective resolution of HNCA and enables near-complete resonance assignment using this single HNCA experiment. We utilize a combination of 2-13C and 3-13C pyruvate as the carbon source for isotope labeling, which suppresses the one bond (1Jαβ) coupling providing enhanced resolution for the Cα resonance and amino acid-specific peak shapes that arise from the residual coupling. Using this approach, we can obtain near-complete (>85%) backbone resonance assignment of a 42 kDa protein using a single HNCA experiment.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Carbon-13 Magnetic Resonance Spectroscopy / methods*
  • Escherichia coli
  • Escherichia coli Proteins / analysis*
  • Isotope Labeling / methods*
  • Magnetic Resonance Spectroscopy
  • Maltose-Binding Proteins / analysis*
  • Pyruvic Acid / chemistry*


  • Escherichia coli Proteins
  • Maltose-Binding Proteins
  • Pyruvic Acid