Effect of pressure and pressure-denaturation on fast molecular motions of solvated myoglobin

The influence of pressure in the range up to 8 kbar on the pico-second dynamics of myoglobin and its hydration shell has been studied by neutron time-of-flight spectroscopy. The quasielastic scattering decreases with pressure due to a reduction in the rate and amplitude of hydrogen bond fluctuations. Irreversible denaturation occurs around 4 kbar. The hysteresis observed on completing the pressure cycle suggests a structural contribution to the dynamic effects of less than 10%: Water interacts more strongly with the unfolded state.