Search for interaction between a soluble protein and a ligand by fluorescence polarization measurement


Fluorescence polarization is widely used for the in vitro study of molecular interactions (e.g. protein-protein or protein-ligand).
It’s a robust, very sensitive, easily miniaturized and easy to use technology since it requires only a simple fluorescence reading.
This is the reason why the fluorescence polarization is used for the search of new ligands.


The principle of the fluorescence polarization is based on :
1- the ability of a fluorophore to be excited by polarized light
2- the ability of the fluorescent molecule to rotate during its "excited" state.

The degree of the fluorescence polarization, defined by the polarization rate (p) or by the anisotropy (r), measures the changes in orientation of the fluorescence emission after excitation of the fluorophore by a polarized light.

Thus, if a small fluorescent molecule is "free", its ability to rotate in the medium will be high, which will induce a depolarization of the fluorescence emission (= Low polarization rate). On the other hand, if it’s bound to a larger molecule such as a protein, its ability to rotate will be greatly reduced, and therefore will not change the direction of fluorescence emission (= High polarization rate).

Development of a binding assay

Format : 96 ou 384 well plates

There are two approaches  :

-  if there is a known ligand of the protein, it is possible to couple it to a fluorophore.

- if no ligand is known: PCBIS has access to collections of fluorescent molecules that can be screened on the target (  

The fluorescent molecule able to bind the target will can be used as a probe to detect the binding of unlabeled molecules to the target.


Notes :

  • Provide 10 to 20 mg of protein (depending on the size of the protein)


Calmodulin binding assay

All models can be adapted to your request.