Determination of the molecular size of BSA by fluorescence anisotropy

This work describes a laboratory experiment to illustrate the usefulness of fluorescence anisotropy in the field of biophysics. Fluorescence anisotropy of dansyl‐labeled BSA was determined in media of increasing glycerol concentrations. The Perrin equation was fitted to the experimental data, obtaining the molecular volume of the protein. The simplicity of the experiment and data analysis helped the students to focus on the relationship between probe anisotropy and rotational diffusion. Additionally, this laboratory exercise has the advantage of using a protein and a probe that are inexpensive and very common in many laboratories.