Optimal control theory enables homonuclear decoupling without Bloch-Siegert shifts in NMR spectroscopy

Nat Commun. 2018 Aug 1;9(1):3014. doi: 10.1038/s41467-018-05400-4.

Abstract

The Bloch-Siegert shift is a phenomenon in NMR spectroscopy and atomic physics in which the observed resonance frequency is changed by the presence of an off-resonance applied field. In NMR, it occurs especially in the context of homonuclear decoupling. Here we develop a practical method for homonuclear decoupling that avoids inducing Bloch-Siegert shifts. This approach enables accurate observation of the resonance frequencies of decoupled nuclear spins. We apply this method to increase the resolution of the HNCA experiment. We also observe a doubling in sensitivity for a 30 kDa protein. We demonstrate the use of band-selective Cβ decoupling to produce amino acid-specific line shapes, which are valuable for assigning resonances to the protein sequence. Finally, we assign the backbone of a 30 kDa protein, Human Carbonic Anhydrase II, using only HNCA experiments acquired with band-selective decoupling schemes, and instrument time of one week.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / chemistry
  • Carbon Isotopes
  • Computer Simulation
  • Humans
  • Magnetic Resonance Spectroscopy*
  • Models, Theoretical*
  • Proteins / chemistry
  • Radio Waves
  • Reproducibility of Results

Substances

  • Amino Acids
  • Carbon Isotopes
  • Proteins