Which type of interaction helps to stabilize the tertiary structure of proteins?

• A. Van der Waals interactions
• B. Hydrophobic interactions
• C. Peptide bonds
• D. Covalent interactions

Answer: (B)

Hydrophobic interactions play a crucial role in stabilizing the tertiary structure of proteins. When proteins fold, nonpolar (hydrophobic) side chains tend to aggregate in the interior of the protein structure, away from the aqueous environment. This aggregation minimizes the exposure of hydrophobic residues to water, leading to a more favorable energy state for the protein. As a result, the overall three-dimensional shape of the protein becomes more stable.

While peptide bonds are essential for linking amino acids together and forming the primary structure, they do not contribute directly to the tertiary structure's stability. Van der Waals interactions, though present, are generally weak and more short-range forces that can occur but are not the primary stabilizing interactions in the context of tertiary structure. Covalent interactions, such as disulfide bonds, do provide stabilization but are not as prevalent as hydrophobic interactions in most proteins.

In summary, hydrophobic interactions are essential to maintaining the folded conformation of proteins by driving the hydrophobic residues inward, which significantly contributes to the protein's stable tertiary structure.