NMR Experiments Summary

• R1/R2 relaxation experiments

  • An extra block of pulses is added following t1 prior to transfer of polarisation from the heteroatom back to 1H via INEPT.
  • Block of pulses varies in length (tau) during each round of relaxation experiment.
  • Decay of signal intensities as a function of tau are proportional to either R1 or R2; fit decays with a single exponential function.
• 1H-15N heteronuclear NOE

  • Compares signal of z-magnetisation of 15N in thermal equilibrium to the z-magnetisation of 15N at equilibrium when the 1H is saturated.
  • Provides information about the motion of individual N-H bond vectors.
• In 1H-15N heteronuclear NOE:

  • Rigid H-N vector ~ 0.9
  • Dynamic H-N vector << 1
• S2 experiments

  • Describes the local motion of the N-H bond relative to the rigid protein.
• In S2 experiments:

  • S2 = 1 indicates rigid motion
  • S2 = 0 indicates isotropic motion