Question

1-Describe fluorescence polarization spectroscopy.

Answer 1

Fluorescence polarization spectroscopy is based on the principle that the light that is emitted by a fluorophore has unequal intensities along different axes of polarization. The principle of Brownian movement and photoselection is made use of in this technique.

Molecules with their absorption transition moment (ATM) aligned with the polarization plane of excitation are preferentially excited. This is called photo-selection, because at the same time molecules with ATM oriented perpendicular to the excitation polarization plane are not excited, they remain in their ground state. This technique was first described by Perrin in the year 1926.

Fluorescence polarization spectroscopy is useful in the study molecular orientation and mobility as well as processes that affect them. Therefore,it has many applications in the field of proteomics, membrane microstructure, viscocity of cytosol and cell membranes and aggregation of proteins in response to signalling.