The characterization of protein-ligand interaction modes becomes recalcitrant in the NMR intermediate exchange regime as the interface resonances are broadened beyond detection. Here, we determined the F low-populated bound-state pseudocontact shifts (PCSs) of mono- and di-fluorinated inhibitors of the BRM bromodomain using a highly skewed protein/ligand ratio. The bound-state F PCSs were retrieved from F chemical exchange saturation transfer (CEST) in the presence of the lanthanide-labeled protein, which was termed the F PCS-CEST approach. These PCSs enriched in spatial information enabled the identification of best-fitting poses, which agree well with the crystal structure of a more soluble analog in complex with the BRM bromodomain. This approach fills the gap of the NMR structural characterization of lead-like inhibitors with moderate affinities to target proteins, which are essential for structure-guided hit-to-lead evolution.

No abstract

The characterization of protein–ligand interaction modes becomes recalcitrant in the NMR intermediate exchange regime as the interface resonances are broadened beyond detection. Here, we determined the 19F low‐populated bound‐state pseudocontact shifts (PCSs) of mono‐ and di‐fluorinated inhibitors of the BRM bromodomain using a highly skewed protein/ligand ratio. The bound‐state 19F PCSs were retrieved from 19F chemical exchange saturation transfer (CEST) in the presence of the lanthanide‐labeled protein, which was termed the 19F PCS‐CEST approach. These PCSs enriched in spatial information enabled the identification of best‐fitting poses, which agree well with the crystal structure of a more soluble analog in complex with the BRM bromodomain. This approach fills the gap of the NMR structural characterization of lead‐like inhibitors with moderate affinities to target proteins, which are essential for structure‐guided hit‐to‐lead evolution.

No abstract