This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
Chaperone proteins play a role in 
Select and explain. 
A. Protein folding, B. Protein misfolding, C. Denaturation, D. All the above
A: Protein folding
Answer: A: Protein folding 
Explanation: Chaperone proteins paicipate in the folding of over half of all mammalian proteins. They can "rescue" unfolded proteins that have become thermodynamically trapped in a misfolded dead end by unfolding hydrophobic regions and providing a second chance to fold productively. Ex: Glutathione can reduce inappropriate disulfide bonds that may be formed upon exposure to oxidizing agents such as O2, hydrogen peroxide, or superoxide Reference: Explanation: Harper's Biochemistry; 30th edition; Chapter 5; proteins: higher Orders of Structure