XL-I Analytical Ultracentrifuge
Analytical ultracentrifugation is a classical method of biochemistry and molecular
biology. Because analytical ultracentrifugation relies on the principal
property of mass and the fundamental laws of gravitation, it has broad
applicability. It is a primary technique requiring no standards for comparison.
Sedimentation can be used to analyze the solution behavior of nearly
any molecule over a wide range of solute concentrations and in a wide
variety of solvents. Thus, while low concentration regimes are of interest
for analyzing tight associations, the ability to characterize the thermodynamic
behavior of a macromolecule at high concentrations makes ultracentrifugation
a good adjunct for drug formulation studies, NMR, or crystallography.
Add to these merits the fact that sedimentation is nondestructive, rapid,
and simple, and it is easy to see why it has endured for more than 70
Analytical ultracentrifugation provides two complementary views of solution
behavior. Although the same instrument is used, different experimental protocols
are employed. Sedimentation velocity provides first-principle, hydrodynamic
information about the size and shape of a molecule, whereas sedimentation equilibrium
provides first-principle, thermodynamic information about the solution molar
mass, association constants, stoichiometries, and solution nonideality. For
many questions, there is no substitute method of analysis.
(T. M. Laue and W. F. Stafford III (1999) Annu. Rev. Biophys. Biomol.