In electrophoresis, how is the rate of migration related to pI?

In electrophoresis, the rate of migration of a protein or molecule is heavily influenced by its isoelectric point (pI). The isoelectric point is the pH at which a molecule carries no net electrical charge. Below its pI, a protein has a net positive charge and will migrate toward the negative electrode (cathode), while above its pI, the protein bears a net negative charge and migrates toward the positive electrode (anode).

The relationship between migration and pI is inversely proportional because as the pH of the medium increases beyond the pI, the charge on the protein also changes, leading to increased speed toward the anode. Conversely, as the pH decreases below the pI, the protein becomes positively charged and migrates toward the cathode. As such, if the pH is close to the pI, the rate of migration slows significantly, since the net charge is minimal. Therefore, the higher the difference in pH from the protein's pI, the faster the migration will generally be.

Understanding this intricate relationship between charge, pH, and migration is crucial for interpreting results in electrophoresis. The concept that the migration speed depends on how far the environment's pH