The technique that separates proteins based on their isoelectric point is Isoelectric Focusing.
- Proteins are amphoteric molecules, meaning they can carry a positive or negative charge depending on the pH of their environment.
- The isoelectric point (pI) of a protein is the pH at which the protein carries no net electrical charge. At this point, the protein is least soluble in water.
- Isoelectric focusing is a powerful technique used to separate proteins based on their pI values. In an electric field, proteins will migrate to the region in a pH gradient where the pH equals their pI.
- During isoelectric focusing, a pH gradient is established in a gel. Proteins are then applied, and they move through the gel until they reach the point where the pH equals their pI.
- At the isoelectric point, proteins stop migrating because they have no net charge, effectively focusing them into sharp bands.
Let's consider why the other options do not separate proteins based on isoelectric point:
- SDS-PAGE: This technique separates proteins based on their molecular weight by denaturing them into linear chains and applying an electrical current across a gel.
- Gel Filtration: Also known as size-exclusion chromatography, this method separates proteins based on their size rather than charge or pI.
- Affinity Chromatography: This technique separates proteins based on specific interactions between a protein and a specific ligand attached to the chromatography matrix.
Therefore, the most suitable method for separating proteins based on their isoelectric point is Isoelectric Focusing.