Dear Dr. Edward d'Auvergne,
When doing model free analysis, I am confused with some general NMR questions,
1. What is the meaning of J(0)? I understand th spectral density
function is the possibility of local magnetic field fluctuate at
certain frequency (say, larmor frequency of 1H or 15N), which is
experienced by 1H or 15N atom and therefore these atom can relax to
equilibrium state. But what is J(0)? J(0) is the possibility of no
local field oscillation?
2. about heteronuclear nuclear Overhauser effect ({1H}-15N NOE),
I understand that if the 1H is saturated and the magnetisation of 1H
will be tranfered to 15N, the peak intensity of 15N will increase
compared with the peak intensity of 15N without saturation of the 1H,
therefore, the NOE value of chemical bond H-N of each amino acid
residue should be larger than 1 because the heteronuclear NOE (1H-15N)
is detected by the ratio of the intensity of {1H-15N}-HSQC peaks in
the presence and absence of proton saturation. But the heteronuclear
NOE (1H-15N) should be less than 1. Are my understanding correct?
Thank you.
With best regards,
Mengjun Xue
J(0) and heteronuclear NOE