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Hyperpolarized nuclear Overhauser enhancement of alanine methyl groups by doubly relayed proton exchange.

Milan ZachrdlaErtan TurhanChristopher PötzlAude SadetPaul R VasosDennis Kurzbach
Published in: Journal of magnetic resonance (San Diego, Calif. : 1997) (2024)
Hyperpolarized water in dissolution dynamic nuclear polarization (dDNP) experiments has emerged as a promising method for enhancing nuclear magnetic resonance (NMR) signals, particularly in studies of proteins and peptides. Herein, we focus on the application of "proton exchange-doubly relayed" nuclear Overhauser effects (NOE) from hyperpolarized water to achieve positive signal enhancement of methyl groups in the side chain of an alanine-glycine peptide. In particular, we show a cascade hyperpolarization transfer. Initial proton exchange between solvent and amide introduces hyperpolarization into the peptide. Subsequently, intermolecular NOE relays the hyperpolarization first to Ala-H α and then in a second step to the Ala-CH 3 moiety. Both NOEs have negative signs. Hence, the twice-relayed NOE pathway leads to a positive signal enhancement of the methyl group with respect to the thermal equilibrium magnetization. This effect might indicate a way towards hyperpolarized water-based signal enhancement for methyl groups, which are often used for NMR studies of large proteins in solution.
Keyphrases
  • magnetic resonance
  • solid state
  • case control
  • computed tomography
  • molecular dynamics simulations
  • ionic liquid
  • contrast enhanced
  • molecular dynamics
  • mass spectrometry
  • room temperature
  • amino acid