Sodium+dodecyl+sulfate-polyacrylamide+gel+electrophoresis+(SDS-PAGE)

__Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) __


 * Basic Description: **

The technique of SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) separates proteins on a polyacrylamide gel on the basis of molecular weight. It also takes into account their electrophoretic mobility. The proteins are treated with negatively charged detergent. This overshadows any charge that the proteins would have had originally and will allow them to migrate through the gel with the electrical field evenly (Seidman). This allows molecular weight to be the main difference being studied without interference from the charged proteins. The detergent also denatures the protein so differential protein shape is also not a factor. That way the proteins no longer have any secondary, tertiary or quaternary structure (Seidman).This technique studies of the molecular weight of proteins as well as the determination of purity of protein preparations. Proteins are treated with a coloring agent (usually coomassie blue) in order for bands to be easily detected.

The denatured proteins are pipette in wells of a stacking gel. When voltage is applied proteins move through the stacking gel which contains a buffer and leading ions that the proteins can move through quickly. Once they reach the running gel, the ions migrate slower, because pore size is small, and there is a higher pH and salt concentration (Voet). This is where proteins molecules will become trapped in the sodium dodecyl sulfate gel depending on their size. Proteins which are smaller will be able to travel further down the gel. A standard molecular weight marker can be added to the wells during the run. This will allow experimental bands to be compared to bands of known molecular weights.




 * Origin and History: **

Gel separation has been used by scientists since the 1950s. It has continuously developed and improved throughout the years. Within the last ten years separation by gel electrophoresis has become widely used is proteomic and genetic studies (Alberts). It continues to be a common application in molecular weight separation and provide unique advances in biochemistry, molecular biology, genetics, gene technology and medicine.


 * Recent Research: **


 * Proteome of E. Coli using 2D Blue Native/SDS-PAGE. J. of Molecular Biology 2011. 409, 655-666. **

This paper is describing an inner membrane protein YidC in E. Coli. They used SDS-PAGE to have a quantitative analysis of the effects of depletion of these enzymes. The SDS-PAGE allowed them to alter protein concentrations and witness the progressive effects at different concentrations. It revealed that they proteins are an important and necessary complex in the E. Coli membrane.


 * Rinaldi, A., Gambuti, A. Evaluation of the astringency of commercial tannins by means of the **
 * SDS-PAGE based method. J. Food Science 2010. 122, 951-956 **

This paper discusses the reaction of salivary proteins with commercial tannins in wine. SDS-PAGE was used to quantify these proteins after the reactions in order to relate them to the astringency of the wine. It was found that astringent capacity became less detectable in more complex wines while in others there was found to be no effect. The scientists wanted to expand of this paper still using SDS-PAGE was analysis.


 * Ram, S., Sharma S. Comparative analysis of LMW glutenin alleles in bread what using allele- **
 * specific PCR and SDS-PAGE. J Cereal Science 2011. 54, 488-493 **

<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">This paper is describing 83 different bread wheat cultivars in studying the diversity of the protein Glu-3loci as well as allelic diversity. SDS-PAGE was used to indicate the percentage of Glu-3 present as well as similar but alternative proteins. They found consistency in the SDS-PAGE but not in PCR amplification. Continued studies are needed to achieve more definite results.


 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Wickstrom, D., Wagner, S. Characterization of YidC Depletion of the Inner Membrean **


 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">References: **

<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Alberts, B. Johnson, A. (2011). Molecular Biology of the Cell 5th ed. New York: Bedford/St. <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Martin Publishing

<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Seidman, L., Moore C. (2009) Basic Laboratory Methods for Biotechnology 2nd ed. New York: <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Pearson Education Inc.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Voet D., Voet J., Pratt C. (2008). Fundamentals of Biochemistry 3rd Edition. New York: Wiley <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Press.