Ultracentrifuge

The ultracentrifuge is a centrifuge optimized for spinning a rotor at very high speeds, capable of generating G forces as high as 1,000,000 G. There are basically two kinds of ultracentrifuges, the preparative and the analytical ultracentrifuge. The second, however, is more theoretically important and we will focus on the discussion of the analytical ultracentrifuge. Theodor Svedberg invented the analytical ultracentrifuge in 1925, and won the Nobel Prize in Chemistry in 1926 for his invention.

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 constants for self associating systems.

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Further information

Analytical Ultracentrifugation as a Contemporary Biomolecular Research Tool

http://www.abrf.org/JBT/1999/December99/dec99cole