Rapid Protein–Ligand Affinity Determination by Photoinduced Hyperpolarized NMR

Measuring the binding affinity of a protein–ligand complex is a routine step of drug design, and the established methods are slow and costly. This paper extends photo-CIDNP screening to affinity determination.

A dissociation constant is obtained in 5 to 15 minutes with 0.1 mg of protein. The method is shown for peptides binding a PDZ domain and for fragments binding PIN1, in the micromolar to millimolar range. Ligands that do not polarise are measured in competition experiments.

The signal reduction seen in photo-CIDNP screening correlates with saturation transfer difference (STD) NMR, and a single scan also informs on the binding epitope.