Hydrophobic interaction chromatography purifies proteins based on what property?

Hydrophobic interaction chromatography (HIC) purifies proteins primarily based on their hydrophobic properties, which refers to the tendency of a molecule to be repelled by water. In HIC, the stationary phase consists of a hydrophobic matrix, and as a protein mixture is applied to the column, proteins are eluted based on their hydrophobicity.

Highly hydrophobic proteins interact strongly with the matrix, while less hydrophobic proteins can be eluted earlier. The separation occurs because hydrophobic regions of the proteins will interact with the hydrophobic surfaces of the stationary phase, allowing for a selective binding process. The elution is typically achieved by gradually increasing the salt concentration or by changing the solvent conditions, which disrupts these hydrophobic interactions and allows proteins to be separated based on how strongly they were bound to the column.

In contrast, size, shape, and charge pertain to different chromatographic techniques. Size exclusion chromatography, for instance, separates molecules based on their size, while ion exchange chromatography separates based on charge. Thus, the focus on hydrophobic properties in HIC makes it a distinctive method for purifying proteins with varying degrees of hydrophobic interaction.