What type of chromatography utilizes hydrophobic beads for protein separation?

Hydrophobic interaction chromatography is specifically designed to separate proteins based on their hydrophobic properties. In this technique, proteins are exposed to a column packed with hydrophobic beads that interact with the hydrophobic regions of the proteins. When a protein mixture is applied to the column, hydrophobic proteins will adhere to the beads, while more hydrophilic proteins will not bind as strongly and will pass through the column more quickly.

The process is commonly used in protein purification because it allows for the separation of proteins based on their hydrophobicity, which can be a critical feature distinguishing different proteins within a mixture. To elute the bound proteins, conditions are gradually changed, usually by increasing the salt concentration or changing the pH, which helps to disrupt the interactions between the hydrophobic groups of the proteins and the hydrophobic beads.

This method is distinct from other types of chromatography like affinity chromatography, which relies on specific binding interactions between a protein and a ligand, ion exchange chromatography, which is based on the charge of the proteins, and size exclusion chromatography, which separates proteins based on their size. Each of these methods has its specific applications and mechanisms of action, making hydrophobic interaction chromatography unique in its approach to protein separation.