Table 1. Summary of current NMR screening methods.

The table outlines the capabilities limitations and requirements of each method as it pertains to the examination of ligand binding to protein targets.

Protein-Target Observed	Limits and Requirements			Permits Identification of:
	Target MW	KD	Isotopic Labeling	Target Binding Site	Ligand Binding Epitope	Ligand Selectivity in a Mixture
aChemical Shift Perturbations	b30 kDa	10−9-10−3	13C and/or 15N	c✓
19F Relaxation and Chemical Shift Perturbations	unlimited	10−6-10−3	19F	d✓
Ligand Observed
Relaxation Rates	unlimited	e10−6-10−3	none		✓	✓
Diffusion Coefficients	unlimited	10−6-10−3	none			✓
Nuclear Overhauser Effects	unlimited	10−6-10−3	none		✓	✓
Magnetization Transfer	unlimited	e10−6-10−3	none		✓	✓
19F Relaxation and Chemical Shift Perturbations	unlimited	e10−6-10−3	fnone			✓

^aThis method requires the use of two-dimensional ¹H-¹⁵N HSQC or ¹H-¹³C HSQC experiments.

^bHigher molecular weight protein-targets may be studied with use of advanced pulse sequences and/or isotopic labeling strategies.

^cPartial or complete resonance assignments are required.

^d19F resonances must be assigned if more than one aromatic residue occurs in the protein.

^eA wider range of binding affinities may be studied if the method is used as a competition based screening experiment.

^fIsotopic labeling is not required if the ligand naturally contains an ¹⁹F moiety.