Proteins and other biomolecules undergo a dynamic transition near 200 K
to a glass-like solid state with small atomic fluctuations. This dynamic transition
can inhibit biological function. To provide a deeper understanding of the
relative importance of solvent mobility and the intrinsic protein energy surface
in the transition, a novel molecular dynamics simulation procedure with the
protein and solvent at different temperatures has been used. Solvent mobility
is shown to be the dominant factor in determining the atomic fluctuations
above 180 K, although intrinsic protein effects become important at lower
temperatures. The simulations thus complement experimental studies by demonstrating
the essential role of solvent in controlling functionally important protein
fluctuations.
