A consistent picture of protein dynamics.

Information about the protein dynamics of myoglobin obtained by x-ray and Mössbauer investigations is analyzed and compared with computer simulations. Computer simulations give correct amplitudes of mean-square displacements but fail in the description of the time dependence of motions. Our model describes protein dynamics at physiological temperatures as an overdamped diffusion-like motion in a restricted space. The fluctuations occur around the average conformation determined by x-ray structure analysis. The gain in entropy drives the molecule into the transition state and, in this way, accounts for its flexibility.