Proteomics/Protein Separations - Centrifugation

Introduction to Centrifugation
Centrifugation is one of the most important and widely applied research techniques in biochemistry, cellular and molecular biology, and in medicine. In the field of proteomics it plays a vital role in the fundamental and necessary process of isolating proteins. This process begins with intact cells or tissues. Before the proteins can be obtained, the cells must be broken open by processes such as snap freezing, sonication, homogenization by high pressure, or grinding with liquid nitrogen. Once the cells have been opened up all of their contents; including cell membranes, RNA, DNA, and organelles will be mixed in the solvent with the proteins. Centrifugation is probably the most commonly used method for separating out all the non protein material. Within the centrifuge samples are spun at high speeds and the resulting force causes particles to separate based on their density.

Uses of Centrifugation
Centrifugation is capable of:
 * Removing cells or other suspended particles from their surrounding milieu on either a batch or a continous-flow basis


 * Separating one cell type from another


 * Isolating viruses and macromolecules, including DNA, RNA, proteins, and lipids or establishing physical parameters of these particles from their observed behavior during centrifugation


 * Separating from dispersed tissue the various subcellular organelles including nuclei, mitochondria, cholorplasts, golgi bodies, lysosomes, peroxisomes, glyoxysomes, plasma membranes, endoplasmic reticulum, polysomes, and ribosomal subunits.

Once the mixture of proteins has been isolated using centrifugation the scientist is then able to use one of several methods to separate out individual proteins for further study. For more information on protein purification/separation see Protein Separations – Chromatography and Protein Separations– Electrophoresis.

Next section: /History of the Centrifuge/

Subscription Based References

 * 1) Sheeler, P. "Centrifugation in Biology and Medical Science." Dept of Biology, California State University, Northridge, California

Open Access References

 * 1) Claude, A. & Potter, J. S. "Isolation of Chromatin Threads From The Reasting Nucleus of Leukemic Cells" The Journal of Experimental Medicine.