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Measuring the Affinity of Challenging Protein Targets

Sean Devenish, Head of Research and Development



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Microfluidic diffusional sizing (MDS) is a method for measuring protein interactions – with affinity and absolute size reported in the same test. In it, fluorescently labeled protein samples are passed through a diffusion chamber alongside a protein-free auxiliary stream. Proteins diffuse from the sample stream to the auxiliary stream based on size, with small proteins moving quickly and larger ones migrating more slowly.

MDS offers several advantages when it comes to measuring protein size and determining binding affinity:

  • It is purely solution based, and as such, provides a more natural environment to limit shifts in protein conformation
  • Because only labeled proteins are measured, MDS can be used with heterogeneous mixtures such as cell lysates and test interactions in complex backgrounds as well as purified buffers
  • MDS supports studies of difficult proteins such as intrinsically disordered proteins, multi-protein complexes, or aggregated fibrils

Watch this webinar from Fluidic Analytics to learn more about MDS, how it can be used to measure not only protein size and binding affinity, but also stoichiometry and protein conformation in protein-protein, protein-antibody, and protein-aptamer interactions!