In proteomics, 2-D electrophoresis is used to separate proteins by their isoelectric point, and then by their mass. This procedure has two main applications: simultaneous identification of mass quantities of proteins, and differential expression .

2-D gel electrophoresis is a multistep procedure that can be used to separate hundreds to thousands of proteins with extremely high resolution. It works by separation of proteins by their pI's in one dimension using an immobilized pH gradient (first dimension: isoelectric focusing) and then by their molecular weights in the second dimension. Gel density in the SDS second dimension can be of a fixed value between 8% and 12% (%T) or a gradient (7.5 - 15%). The resulting gel is then Coomassie Blue or silver stained for viewing the protein spots. All gels are then scanned using a GS-800 calibrated densitometer from which one can obtain TIFF files of the image. We also can perform image analysis using PDQuest software version 7.0 from Bio-Rad. This software permits the comparison and analysis of replicates of gels to determine statistically and scientifically meaningful spots. Proteins of interest then can be excised from the gel, characterized and identified by mass spectrometry.

To summarize, 2-D gel electrophoresis process consists of these steps:

1. Sample preparation
2. First dimension isoelectric focusing
3. Second dimension gel electrophoresis
4. Staining
5. Imaging analysis

See also

• electrophoresis

External links

• A 2-D electrophoresis tutorial on the web site of the Parasitology Group at Aberystwyth University http://www.aber.ac.uk/parasitology/Proteome/Tut_2D.html
• Discussion forum about 2D gel image analysis http://forums.deltastat.org