Fluorescence spectroscopic methods to analyze drug-tubulin interactions.

Fluorescence spectroscopy has been extensively used to characterize ligand binding to tubulin and microtubules. The inherent advantages of fluorescence spectroscopic methods lie in their ease, sensitivity to local environmental changes, and ability to describe the protein-ligand interactions qualitatively as well as quantitatively in equilibrium conditions. In this chapter, we have described how fluorescence spectroscopy has been used to decipher molecular interaction between a wide variety of ligands and tubulin. Particularly, we have discussed its use to characterize the binding parameters of ligands that are known to bind to three important sites in tubulin namely the vinca domain, the colchicine binding site, and the taxol site. These are the sites where most of the microtubule-targeted anticancer agents bind to tubulin. An understanding of the interaction between tubulin and small molecule inhibitors can assist in understanding the cellular effects of these inhibitors. This will also help in developing molecules that have higher binding affinity to tubulin and can serve as potent anticancer agents.