What describes the tertiary structure of a protein?

The tertiary structure of a protein refers to its overall three-dimensional shape, which is crucial for its function. This structure arises from the interactions between the side chains of the amino acids that make up the polypeptide chain, including hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals forces. The specific arrangement and folding into a unique shape allows the protein to perform its specific biological functions, such as catalyzing reactions, providing structural support, or facilitating communication between cells.

This three-dimensional conformation is distinct from the primary structure, which refers to the linear sequence of amino acids, and the secondary structure, which includes local folded structures such as alpha-helices and beta-sheets. The idea of multiple subunits interacting pertains more to quaternary structure, which involves the assembly of multiple polypeptide chains into a single functional protein complex. Regular patterns of coils describe aspects of secondary structure rather than the complete three-dimensional shape of the entire protein.