What determines the tertiary structure of a protein?

The tertiary structure of a protein is primarily determined by the interactions and bonds formed between the side chains of the amino acids that make up the polypeptide chain. These side chains, or R groups, can interact through various types of bonds, including hydrogen bonds, ionic bonds, Van der Waals forces, and disulfide bridges.

These interactions are crucial as they help fold the protein into its three-dimensional shape, which is essential for its function. The specific orientation and chemistry of the side chains lead to a unique spatial arrangement that stabilizes the structure, allowing it to perform its biological role effectively.

The sequence of amino acids is foundational for determining how the side chains will interact; however, the direct stabilization and organization into tertiary structure come from the bonds and interactions among these side chains rather than the sequence itself. Hydrogen bonds between backbone components contribute to the secondary structure of the protein, while the number of subunits involved pertains to quaternary structure, not tertiary structure. Thus, the bonds among the side chains are the key factor in establishing the protein's tertiary configuration.