Protein folding can be studied using a solution of purified protein and a denaturant (urea), a solvent that interferes with noncovalent interactions. Which of the following is observed after the denaturant is removed from the protein solution?
(a) The polypeptide returns to its original conformation.
(b) The polypeptide remains denatured.
(c) The polypeptide forms solid aggregates and precipitates out of solution.
(d) The polypeptide adopts a new, stable conformation.
Answer: A