Two-dimensional gel electrophoresis, (2-DE or 2D electrophoresis), is a form of gel electrophoresis commonly used to isolate the proteins in a sample for further characterization by mass spectroscopy. Mixtures of proteins are separated in the 1st dimension by their charge (isoelectric focusing (IEF)). Then in the 2nd dimension, proteins are separated by their size (molecular weight). This video shows the part 6- reduction and alkylation.