The main source of geometric information used in NMR structure determination of biomolecules lies in short interproton distance restraints derived from Nuclear Overhauser effect (NOE) measurements.

The NOE observed for two spins A and B at short mixing times is proportional to the inverse sixth power of the distance between them, <1/r_AB⁶>, so its intensity falls off very rapidly with increasing distance between proton pairs. Consequently, NOEs usually are observed only for proton pairs separated by 5-6 A.

1D Experiments Selective 1D NOESY Selective ge-1D NOESY

2D Experiment 2D NOESY ge-2D NOESY ge-2D HMQC-NOESY ge-2D HSQC-NOESY 2D w1-edited NOESY 2D w2-edited NOESY 2D w1,w2-edited NOESY

3D Experiment 3D HMQC-NOESY 3D HSQC-NOESY 3D NOESY-HMQC 3D NOESY-HSQC 3D HSQC-NOESY-HSQC

4D Experiment 4D HMQC-NOESY-HMQC

Miscellaneous 15N {1H} NOE 13C {1H} NOE

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2D/3D/4D experiments to measure NOEs in proteins. Correlation between NOE experiments Isotope edited/filtered NOE experiments NOEs vs secondary structure Diagonal Suppression in NOESY experiments