Practice question

Nuclear Overhauser Effect provides distance information via through-space dipole-dipole cross-relaxation, decaying as inverse sixth power of internuclear separation, observable up to about 0.5 nanometer. Intensity depends on molecular tumbling and proximity, not on covalent bonds. Through-bond scalar coupling underlies COSY and TOCSY spectra, showing connectivity. Therefore statement describing NOEs as through-bond is false. NOESY experiments exploit dipolar mechanism to generate restraints for three-dimensional structure calculation of proteins, nucleic acids, and polysaccharides, fundamental distinction taught in biophysical chemistry and structural biology courses for interpreting spectra correctly.