Centrifugation of DNA, Proteins, and
Using the Ultracentrifuge an investigator can isolate and purify a plasmid which he has transfected into either E. Coli or some other transfection vehicle. The RIC Facility has a protocol for isolating and purifying plasmids located at the bottom of this page. After the DNA has been isolated from the remainder of the cell lysate, the DNA is placed into a ultracentrifuge tube. This tube has Ethidium Bromide placed into it to visualize the DNA, and the tube is spun in the Ultracentrifuge overnight. Here are the results:
In this image you can see the band about an inch up from the bottom of the tube. This is the Plasmid. You can now take this band out using a needle and syringe and purify it to remove the Ethidium Bromide and other impurities. After this purification you are left with the DNA plasmid in water.
Proteins and Viral Particles
A cesium choride gradient can also be used to seperate proteins and viral particles. Located below is information on how to purify viral particles using the ultracentrifuge.