Protein Protein Assays

Label-Free Protein - Protein Assays

The animation on the left depicts a label-free protein-protein interaction assay.  A baseline measurement is made followed by the addition of protein binding partner, after which a second measurement is made.  The endpoint data indicate whether or not a binding event occurred.

Label-free protein-protein interaction assays have been demonstrated on a number of systems.

Kinase/ Peptide

Cytokine/Cytokine Receptor

Cytokine/ IgG

Antibody/ Peptide

Antibody/ Antigen (in serum)

Multiplex Multiple Cytokine 

Traditional protein-protein interaction assays rely heavily on several components.  Most assays available today measure interaction indirectly.  For example, the disruption of a functional activity, or the presence or absence of a downstream by-product.  Other assays also require the use if radiometric reagents resulting in added safety and disposal precautions.  Additionally, to monitor disruption of a functional activity, the natural ligand must be identified, and one or both binding partners must be labeled thereby disrupting the native state.  Functional measurements also restrict such work to active protein forms (inactive proteins become challenging).

Label-free protein-protein assays provide direct binding measurement.  The assays can also be multiplexed.  Sample applications include enzyme inhibition, competition assays, and ligand determination where the natural ligand is unknown.