Purification+through+Centrifugation

=__Purification Through Centrifugation __=


 * Basic Description: **

Purification through centrifugation is a popular technique used in cell biology that allows one to extract a protein from a mixture or matrix. Centrifugation separates components based on size and density. A solution is placed in a centrifuge tube, which is then placed into the rotor of a centrifuge machine. When the machine is turned on, the rotor experiences rapid rotations which generate large centrifugal forces. These forces cause particles to sediment. The largest sized particles experience the largest centrifugal forces, and thus move the quickest. Depending on the speed of the centrifuge and the length of time that the solution is centrifuged for, different components of the cell can be deposited. The process can be repeated numerous times until properly purified (Alberts, et al., 2008). The solid sediment on the bottom of the tube is called the pellet and the liquid remaining in the tube is called the supernatant.


 * Purpose of Technique: **

The purpose of centrifugation is to extract a protein from a mixture or matrix in order to purify it for further examination or use. Centrifugation allows one to determine the density and/or size of a protein. It also allows for the analysis of specific components of a protein.


 * Origin and History: **

The process of centrifugation started in the mid-15th century when hand-operated centrifuges were created to separate milk. In 1864, Antonin Prandtl developed the first dairy centrifuge to separate cream from milk, and this is when the centrifuge was officially commercialized. In 1869 Friedrich Miescher used a centrifuge in a lab for the first time to isolate a cell organelle. Since this time, there have been multiple developments made to the original centrifugation system, making it more and more complex. (Buie, 2010).


 * Recent Research: **

A recent research article that used centrifugation is “The impact of cushioned centrifugation protocols on semen quality of stallions.” In equine breeding programs, stallion semen is often centrifuged to increase sperm concentration in extended semen and/or reduce seminal plasma concentration for insemination of mares. This study set out to determine if either sperm concentration of extended semen following centrifugation, or if decreased cushion-fluid volume and increased sperm number during centrifugation, would affect the quality of stallion sperm. It was concluded that both methods are equally efficient in affecting stallion sperm quality. Both methods, requiring centrifugation at different times, and containing different amounts of supernatant and precipitate (sperm), were found to have a positive impact on sperm quality. (Bliss, et al., 2012).

A second research article that used centrifugation is “Oocyte recovery post human follicular fluid centrifugation in modified natural cycle and achieving embryo.” In this study, a woman with a sever ovarian defect underwent a procedure called a modified natural cycle. Human follicular fluid (HFF) was centrifuged twice in order to collect two oocytes. Intracytoplasmic sperm injection (ICSI) was then performed on both oocytes, and a live birth was achieved. Centrifugation played an important role in this procedure because it allowed the gathering of both oocytes which led to the development of two embryos. (Ferrieres, et al., 2009).

A third research article that used centrifugation is “Separation of nanorods by density gradient centrifugation.” Because the experimental conditions necessary for the synthesis of well-defined nanoparticles are usually difficult to have power over, post-synthesis separation of these nanoparticles by size and shape is essential. In this study, density gradient centrifugation is used to separate gold nanorods. This allowed the authors to analyze the centrifugal sedimentation behaviors of gold nanorods. It was found through centrifugation that nanorod sedimentation rates depend highly on both their mass and shape. Centrifugation revealed that long and thin yet heavier rods sediment slower, and some rods and spheres with different shapes and masses may not separate at all. (Xiong, et al., 2011).


 * References: **

Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2008). Molecular Biology of the Cell (5th ed.). New York: Garland Science

Bliss, S.B., Voge, J.L., Hayden, S.S., Teague, S.R., Brinsko, S.P., Love, C.C., et al. (2012). The impact of cushioned centrifugation protocols on semen quality of stallions. Theriogenology, 77(6), 1232-1239.

Buie, J. (2010). Evolution of the Lab Centrifuge. Lab Manager Magazine. Retrieved October 12, 2012, from [|http://www.labmanager.com][|/?articles.view/articleNo/3666/article/Evolution-of-the-Lab-Centrifuge]

Ferrieres, A., Reyftmann, L., Pellestor, F., Hedon, B., Dechaud, H., & Hamamah, S. (2009). Oocyte recovery post human follicular fluid centrifugation in modified natural cycle and achieving embryo. Reproductive BioMedicine Online, 18(5), 671-673.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Xiong, B., Cheng, J., Qiao, Y., Zhou, R., He, Y. (2011). Separation of nanorods by density gradient centrifugation. Journal of Chromatography A, 1218(25), 3823-3829.