Protein-Ligand Interactions

Protein-Ligand Interactions

Epi-readers are proteins which recognise post-translational modifications on histones and play key roles in transcriptional regulation and chromatin remodelling. Examples include bromodomains which recognise acetylated lysine residues, and chromodomains and malignant-brain tumour domains which recognise methylated lysine residues. Such epi-readers are a major focus in drug discovery due to their role in oncology and inflammatory diseases

BRD4(1) Assay

  • We have developed an assay for bromodomain, BRD4(1), whereby binding of a histone H4 acetylated peptide containing a FLT modulator residue, M, results in a change in fluorescence lifetime of 9AA labelled BRD4(1)
  • Using our in-house protein engineering technologies, site-specifically 9AA labelled BRD4(1) was provided in good yield and excellent purity.


  • Binding of 9AA labelled BRD4(1) bromodomain to an acetylated histone H4 peptide is reported through dose-dependent changes in FLT. The analogous unacetylated peptide does not cause a similar change in FLT confirming the ability of the system to report protein-ligand binding
  • The FLEXYTE™ BRD4(1) assay was validated for inhibitor screening using the small molecule inhibitor, JQ1(+) and DMSO (an acetyl-lysine mimic) with IC50 values in good agreement with those reported in the literature
  • A Z’-factor of 0.62 demonstrates the potential of the assay for HTS
  • This platform technology can be readily developed for monitoring other protein-protein or protein-ligand interactions, as well as providing a platform technology for assaying Epi-reader proteins.

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