What characteristic of amino acids influences the shape of proteins in an aqueous environment?

The characteristic of amino acids that influences the shape of proteins in an aqueous environment is indeed the combination of both their hydrophobic and hydrophilic natures. In an aqueous environment, proteins fold into specific three-dimensional shapes primarily due to the interactions of the amino acids that make them up.

Amino acids can be classified based on their side chains as either hydrophobic (water-repelling) or hydrophilic (water-attracting). Hydrophobic amino acids tend to cluster together in the interior of the protein, away from water, in an effort to avoid contact with the aqueous environment. In contrast, hydrophilic amino acids are found on the exterior, where they can interact favorably with water molecules.

This dual nature creates a balance that is crucial for proper protein folding and stability. The varying interactions between the hydrophobic core and the hydrophilic surface determine how proteins adopt their functional shapes, which is essential for their biological activity. Therefore, understanding both hydrophobic and hydrophilic characteristics is key to grasping how proteins achieve their final forms in water.