Using Paramagnetic Probes to Study Structural Transitions in Proteins

When a nitroxide radical is bound to a protein in solution, the shape of its spectrum and its relaxation properties depend on its interactions with its environment. These “paramagnetic probes” can be used to study structural transitions in proteins, which are very important phenomena which are currently poorly understood. By labelling an appropriately selected site, it is possible, for example, to monitor conformational changes in an enzyme induced by its interaction with its physiological partners. It is also possible to draw a “mobility map” to identify the domain involved in folding of an “intrinsically disordered protein” induced by its interaction with another protein.