Surface Plasmon Resonance (SPR)

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 Molecular we use the Biacore 8K system for our SPR work. It is recognised as a world-leader for biophysical characterisation 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 immobilisation chemistries to competition-based or complex-based binding studies, maximising the chances of successful assay development for your target

The response plot (top) and sensorgrams (bottom) demonstrate us testing the robustness of an immobilised 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

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

Contact us at info@charnwood-molecular.com to find out more. 

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