Kinetic and spectroscopic probes of motions and catalysis in the cytochrome P450 reductase family of enzymes

There is a mounting body of evidence to suggest that enzyme motions are linked to function, although the design of informative experiments aiming to evaluate how this motion facilitates reaction chemistry is challenging. For the family of diflavin reductase enzymes, typified by cytochrome P450 reductase, accumulating evidence suggests that electron transfer is somehow coupled to large-scale conformational change and that protein motions gate the electron transfer chemistry. These ideas have emerged from a variety of experimental approaches, including structural biology methods (i.e. X-ray crystallography, electron paramagnetic/NMR spectroscopies and solution X-ray scattering) and advanced spectroscopic techniques that have employed the use of variable pressure kinetic methodologies, together with solvent perturbation studies (i.e. ionic strength, deuteration and viscosity). Here, we offer a personal perspective on the importance of motions to electron transfer in the cytochrome P450 reductase family of enzymes, drawing on the detailed insight that can be obtained by combining these multiple structural and biophysical approaches.