Electrophoresis

When placed in an electric field, molecules with a net charge like as proteins will move towards one electrode or the other a phenomenon which is known as electrophoresis. The larger the net charge the quicker the molecule will move. In polyacrylamide gel electrophoresis PAGE the electrophoretic separation is carried out in a gel that serves as a molecular sieve.  Small molecules move readily by the pores in the gel, while larger molecules are retarded. The gels are generally  made  of  polyacrylamide   that  is  chemically  inert  and  that  is readily  formed  through the polymerization  of acrylamide.  In the gel the pore sizes can be managed through choosing appropriate concentrations of acrylamide, methylene bisacrylamide and the cross-linking reagent.  The higher the concentration of acrylamide used the smaller the pore size in the ?nal gel. The gel is generally cast among two glass plates divided through a space of 0.5–1.0 mm. The protein  sample  is added  to wells  in the  top  of the  gel,  that  are  formed  through placing a plastic comb in the gel solution before it sets. A blue dye (bromophenol blue) is mixed with the protein sample to aid its loading on to the gel because  bromophenol  blue  is  a  small  molecule  it  also  migrates  fastly by the gel during electrophoresis  and so denote  the progress of electrophoresis.