A technique that can be used to separate proteins based primarily on the presence of non-polar residues on their surface is called A) ion-exchange chromatography. B) gel filtration chromatography. C) affinity chromatography. D) gel electrophoresis. E) hydrophobic interaction chromatography.

E) hydrophobic interaction chromatography.

Explanation:

Hydrophobic interaction chromatography (HIC) is a methodology used to separate protein molecules depending on their hydrophobicity. HIC enables the separation and purification of proteins by using a reversible interaction between the target protein and the hydrophobic ligand of a HIC resin such as, for example, methacrylate-based beads. This interaction is influenced by the running buffer (high salt concentrations favor hydrophobic interactions). HIC enables the separation of proteins under low denaturation conditions, thereby preserving their biological functions.