  Molecular dynamics simulations of myoglobin and aspartate aminotransferase,
with explicit solvent, are shown to accurately reproduce the experimentally
measured molar volumes. Single amino-acid substitution at VAL39 of aspartate
aminotransferase is known to produce large volumetric changes in the enzyme,
and this effect is demonstrated in simulation as well. This molecular dynamics
approach, while more computationally expensive that extant computational
methods of determining the apparent volume of biological systems, is quite
feasible with modern computer hardware and is shown to yield accurate
volumetric data with as little as several nanoseconds of dynamics.
