Surface Plasmon Resonance

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Surface plasmon resonance (SPR) is well-known and well-regarded as a powerful and highly sensitive technique for the study of biomolecular interactions.

Within drug discovery, one common application is to measure the interaction of a molecule (in SPR termed ‘analyte’ – a small molecule, a protein, an antibody) with another molecule held on a sensor chip surface (in SPR termed ‘ligand’ – usually a protein or different antibody).

Under certain conditions, SPR can measure both the affinity (KD) of the interaction and the kinetics (on-rate (ka) and off-rate (kd). These parameters are highly valuable at all stages of a drug discovery project.

For example a series of hits can be ranked and triaged by their binding affinities, their on-rates or their off-rates – the ideal metric to use will depend on the specific interaction or disease area being targeted.

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At Charnwood Discovery we use the Biacore 8K system for our SPR work. It is recognized as a world-leader for biophysical characterization of molecular interactions. Benefits include:

  • Low protein consumption – extracting the maximum amount of data from relatively small amounts of recombinant protein, allows us to work with difficult to purify targets
  • High throughput – hundreds to thousands of compounds can be screened in a day, allowing a rapid start to any project. With 8 channels to simultaneously work with, affinities are rapidly determined allowing key project decisions to be reached quickly
  • High sensitivity – the Biacore 8K has excellent sensitivity and can detect binding affinities from the picomolar to millimolar
  • High flexibility – many approaches to developing an SPR assay are available, from different immobilization chemistries to competition-based or complex-based binding studies, maximizing the chances of successful assay development for your target
assay development
SPR-Figure-1

The response plot (top) and sensorgrams (bottom) demonstrate us testing the robustness of an immobilized protein surface by repeated binding of one concentration of a tool compound.

By assessing the extent to which the binding response reduces with increasing cycle number we can gauge how robust our surface is and how amenable to long compound-binding studies it is.

Below we see the 1:1 binding model fit (left) and the steady-state affinity fit (right) for the interaction between the protein BRD4 and tool compound MS436 (1:1 Binding Kinetics: ka 6.1e5 M-1 s-1, kd 1.3e1 s-1, KD 210 nM. Steady State Affinity: 190 nM).

The sensorgrams are very high quality and enable us to fit the kinetics and affinity of the interaction with high confidence

SPR-Figure-2

Our expert team can discuss your needs with you and how SPR is best placed to progress your drug discovery project.

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