Electrophoresis

The electrophoresis equipment can have several designs. The simplest approach is the moving boundary technique (Figure 3). The charged molecules (i.e., proteins) to be separated are electrophoresed upward through a buffer solution toward electrodes immersed on either side of a U-shaped tube. The individual proteins are resolved because they have different mobilities as described above. This technique separates the biomolecules on the Figure 1. Illustration by Hans & Cassidy. Courtesy of Gale Group. basis of their charges. Positively charged molecules migrate toward the negative electrode (cathode) and negatively charged particles move to the positive electrode (anode). The migration of the particles to the electrodes can be followed by instruments which measure the refractive index or absorption of light by the solution.

The most important class of electrophoresis is zone electrophoresis. In zone electrophoresis, the sample to be separated is applied to a solid matrix through which it migrates under the force of an applied electric potential. Two major classes of zone electrophoresis will be discussed below.