The isoelectric point is the pH at which a molecule is neutral. If a protein or amino acid possesses many acidic side chains, its isoelectric point will be low. Conversely, if a protein or amino acid possesses many basic side chains, its isoelectric point will be high. This characteristic can be used to separate proteins through a process called electrophoresis.
Electrophoresis takes advantage of varying isoelectric points to separate proteins.
- A pH gradient is set up on a gel matrix
- An electric current is passed through the gel to create an anode and cathode.
- Proteins which are in a region below is isoelectric point (low pH) will be positive and migrate to the cathode until it reaches its isoelectric point.
- Proteins which are in a region above its isoelectric point (high pH) will be negative and migrate to the anode until it reaches its isoelectric point.
The following figure demonstrates the process of electrophoresis: