We learned an experiment that studied the denaturation and renaturation of a protein (ribonuclease A), what did the experiment find (suggest)? A. Protein folding is very slow. B. Protein folding always requires assistance from other proteins. C. Protein tertiary structure is dictated by its amino acid sequence. D. The native fold of a protein is at its highest energy conformation.
The Correct Answer and Explanation is:
The correct answer is C. Protein tertiary structure is dictated by its amino acid sequence.
The experiment you are referring to likely involved the denaturation and renaturation of ribonuclease A, a protein that catalyzes the hydrolysis of RNA. Denaturation involves the disruption of the protein’s native structure, typically caused by changes in temperature, pH, or the addition of chemicals like urea or guanidine hydrochloride. Renaturation refers to the process of the protein returning to its original functional form once the denaturing conditions are removed.
The findings of this experiment suggest that the amino acid sequence of a protein contains all the necessary information for it to fold into its correct tertiary (three-dimensional) structure. This concept is often referred to as the “Anfinsen’s Dogma,” based on the work of biochemist Christian Anfinsen. He showed that when ribonuclease A was denatured and then the denaturants were removed, the protein spontaneously refolded into its functional conformation, indicating that the protein’s tertiary structure was determined solely by its amino acid sequence, without the need for additional assistance from other proteins.
This suggests that the native fold of a protein (its most stable, functional form) corresponds to the lowest energy conformation that is specific to the sequence of amino acids it contains. Therefore, protein folding does not always require assistance from other proteins (ruling out B), and it is not a slow or high-energy process as implied by options A and D.
Thus, the experiment supports the idea that the native conformation of proteins is inherently encoded in the sequence of amino acids, which is a fundamental principle of molecular biology.
