Entropy change of protein and water during the denaturation of cytochrome P450s

Cytochrome P450s are ubiquitous hemeprotein monooxygenases that catalyse numerous biochemical reactions, and the investigation on them is of significance to both the protein engineering and human health. We found that the thermophilic cytochrome P450, CYP119, may achieve both greater thermal stability and higher structural flexibility simultaneously by keeping larger entropy at the native state. Although we have measured the thermodynamic curves during the denaturation of both CYP101A1 and CYP119, it’s quite difficult to distinguish the entropy change of protein and water. We believe water molecules play an important role of protein stability, especially in the functional state. Fortunately, combining inelastic neutron scattering and protein perdeuteration, we may obtain the density of states of protein and water, respectively, and calculate the entropy change.