A series of hydrophobic side chains will congregate together as a protein folds in an aqueous solution and be stabilized by the hydrophobic effect.

Here's a breakdown:

* Hydrophobic effect: Water molecules are polar and form strong hydrogen bonds with each other. Nonpolar molecules (like hydrophobic side chains) disrupt these hydrogen bonds and are therefore unfavorable in an aqueous environment. To minimize this disruption, hydrophobic side chains cluster together in the interior of the protein, away from the water.

* Stabilization: This clustering is not driven by a direct attraction between hydrophobic side chains. Instead, it is a consequence of the increased entropy (disorder) of the surrounding water molecules when the hydrophobic groups are buried within the protein. This increase in entropy drives the folding process and stabilizes the folded protein structure.

In summary, hydrophobic side chains in a protein are driven to come together in an aqueous environment to minimize the disruption of water molecules and increase the overall entropy of the system. This is a major driving force in protein folding.