Denaturing followed by renaturing of a protein O O O demonstrates that primary structure dictates tertiary structure. always results in the protein regaining its function. requires heat. requires breaking and reforming disulfide bonds
The Correct Answer and Explanation is:
Correct Answer: Demonstrates that primary structure dictates tertiary structure.
Explanation:
Denaturing and renaturing of a protein demonstrate that the primary structure dictates the tertiary structure of the protein.
Proteins are composed of amino acids arranged in a specific sequence known as the primary structure. This linear sequence of amino acids determines how the protein will fold into its functional three-dimensional shape, or tertiary structure. When a protein is denatured, its higher-level structures—secondary, tertiary, and sometimes quaternary—are disrupted, usually due to external stress such as heat, pH changes, or chemical agents. Denaturation does not break peptide bonds (which make up the primary structure), but it does affect hydrogen bonds, hydrophobic interactions, ionic bonds, and sometimes disulfide bridges.
If the denaturing agent is removed and the environment returns to favorable conditions, some proteins can spontaneously refold into their original functional conformation. This process is called renaturation. The ability of a protein to renature properly without external assistance proves that the information needed for correct folding is contained entirely in the amino acid sequence, i.e., the primary structure. This was famously demonstrated in experiments by Christian Anfinsen with ribonuclease A, which regained its structure and function after denaturation and renaturation.
Let’s examine the other choices:
- “Always results in the protein regaining its function” is incorrect. Not all proteins can refold correctly; some may aggregate or misfold.
- “Requires heat” is also incorrect. While heat is a common denaturing agent, denaturation can also be induced by acids, bases, detergents, or urea.
- “Requires breaking and reforming disulfide bonds” is only partially true. Disulfide bonds may be involved in stabilizing the tertiary structure, but they aren’t always broken during denaturation, and not all proteins contain disulfide bonds.
In conclusion, successful renaturation after denaturation demonstrates that a protein’s tertiary structure is governed by its primary structure.