Competition analysis

- Discover non-competitive ligands and allosteric sites


Label free competition experiments enable a rapid identification of second-site binders (allosteric binders) and deconvolution of fragment binding. This facilitates lead generation and serves as input for prioritization among fragments for co-crystallization. Fragments identified to bind concurrently to neighboring binding sites can provide starting points for fragment linking.


  • Identification of binders to known binding sites
  • Identification of allosteric binders
  • Identification of novel bindning sites
  • Deconvolution of fragment binding within the same binding site

Technical Details

Following an identification of binders by SPR biosensor-based assays, a primary competition screen where fragment hits are allowed to compete with a known ligand, can be applied to identify allosteric binders. In this assay, the known ligand is used to saturate the binding site and the effect of adding a fragment is monitored (1st degree competition screen). The competition experiment between second-site binders requires a modified protocol. By accounting for the non-saturating conditions in combination with differences in KD, MW and degree of unspecific signals, robust measures of competition can be calculated.


Example of a screening funnel including a step (1st degree competition screen) involving competition with a known inhibitor to filter out allosteric binders and a second step aimed at deconvolution of fragment binding.

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