# Proteomics/Protein Separations - Centrifugation/History of the Centrifuge
## History of the Centrifuge

Centrifuges were first used in the mid-1400s for processes such as separation of milk. These early machines were hand driven and could reach speeds up to 3000rpm. By 1912, new centrifuges were developed which ran on electrical power.

### Svedberg and the Ultracentrifuge

In 1926 Theodor Svedberg (1884-1971) received a Nobel Prize for his work in colloid chemistry and invention of the ultracentrifuge. During the 1920’s-30’s his group built a number of ultracentrifuges capable of reaching 900,000kg. These models had very small rotors. Larger rotors were used for routine work. Svedberg used his centrifuge to determine the molecular weights and subunit structure of highly complex proteins such as hemoglobin. The results of these studies shaped new ideas about the structures of proteins. His later work in nuclear chemistry helped improvements of the cyclotron. Svedberg also aided in the development of electrophoresis by one of his students, Arne Tiselius (see Protein Separations– Electrophoresis).

### Isolating Cellular Components

During the early 1930s Martin Behrens worked to improve density gradient techniques involving centrifugation. He has been credited with the introduction of density gradient centrifugation as a means of separating and isolating cells and subcellular components. His approaches to tissue fractionation, as well as those of Bensley and others, had a major aim the isolation from disrupted cells of one or more identifiable components that could then be physically and chemically characterized. The principal method of analysis was light microscopy. In this sense, their approach was strictly preparative and is to be contrasted with the more analytical procedures of Claude and his successors who were concerned with the purity of centrifugally isolated fractions, examining their enzymatic activities and questioning whether certain properties were unique to specific types of sub-cellular particles or were more broadly distributed.
In 1942 Dr. Albert Claude and Dr. James S. Potter published a paper entitled “Isolation of Chromatin Threads from the Resting Nucleus of Leukemic Cells”. In this landmark work they outlined a process involving a series of centrifugation steps. During these steps either the supernate or the sediment was collected until the finally “chromatin threads” were retrieved from the final sediment.

## Modern Centrifuges

In 1940 SPINCO produced the first commercial ultracentrifuge. Beckman Instruments bought out Spinco in 1954 and continued making ultracentrifuges. This company is now known as Beckman Coulter and is still a major manufacturer of centrifuges today. A picture of a Beckman Coulter Avanti J-E centrifuge can be seen below. Many improvements in the design of these machines lead to the tool used today. The drive system was upgraded to high speed motors and the material used for the rotor was updated. Original rotors, such as those built by Svedberg, were made of tensile steel. Today materials such as aluminum alloys and titanium are used to withstand high centrifugal forces. Vacuum systems were added to reduce friction and maintain temperature control. The development of other tools, such as electron microscopes, allowed researchers to better examine the particles being centrifuged. Scientists were then able to visualize organelles separated with the ultracentrifuge and characterize their structure-functional relationships.
Many different centrifuges are available today. They range in size from bench top centrifuges basket volumes of 1.2 liters and maximum loads of 1.5 kg like the eppendorf becnhtop centrifuge seen below to large free standing centrifuges with basket volume of 5 liters and maximum loads of 6 kg or larger. Some of the smaller centrifuges have maximum rotational speeds of less than 300rpms while the larger machines can reach up to powers of 10,000rpms at a time.
Next section: How the Centrifuge Works

## References
### Subscription Based References

Future Listing of Subscription Based References

### Open Access References

* Buckley, Nancy. "Lecture 5: Centrifugation" Biological Sciences Department, California State Polytechnic University.
* "Centrifuge, Centrifuges & Centrifugation" Fronine Laboratory Supplies.
* Claude, A. & Potter, J. S. "Isolation of Chromatin Threads from the Resting Nucleus of Leukemic Cells" Journal of Experimental Medicine.
* De Duve, C. & Beuafay, H. "A Short History of Tissue Fractionation" The Journal of Cell Biology: Volume 91, No. 3, PT. 2 December 1981, p. 293-299.
* "Meischer's Discovery: A DNA Adaptive Laboratory" The Institute for Genomic Research
* "Peeler Centrifuges, Basket Centrifuges and Solvent Extraction Equipment for Chemical and Pharmaceutical Industries" Rousselet Robatel Catalog.
* "Theodor Svedberg Definition" From Answers.com.
* "Wikipedia: Theodor Svedberg"