With the analytical ultracentrifuge, the sample being spun is observable through an optical detection system that allows the operator to observe the sample concentration in real time during the experiment. With modern instrumentation, these observations are electronically stored and computerized and can be analyzed after the fact. Two kinds of experiments are commonly performed on these instruments, sedimentation velocity experiments and sedimentation equilibrium experiments. The first are sensitive to both the shape and molecular weight of the sample being studied, whereas the second are insensitive to the shape, but are sensitive to the molecular weight of the sample being studied.
The kinds of information that can be discerned from a good analytical ultracentrifuge include the shape of macromolecules, the conformational changes in macromolecules, subunit stoichiometry of macromolecules, approximate molecular weights, and equilibrium constantss for self associating systems.