Question

Which among the following statements are true with respect to protein denaturation?

• A. There may be an increase in $\alpha$-helix and $\beta$-sheet structure
• B. It is an irreversible process
• C. When fully denatured, globular proteins resemble a random coil
• D. The peptide bonds are broken

Hint:

Denaturation refers to the unfolding of a protein's secondary, tertiary, and quaternary structures, but does not break peptide bonds. It may lead to random coil formation or secondary structures like $\alpha$-helix and $\beta$-sheets.

Answer 1

The Correct Option is A, C

Protein denaturation refers to the process where proteins lose their three-dimensional structure due to external factors such as heat, chemicals, or pH changes. This process disrupts the non-covalent interactions (such as hydrogen bonds and hydrophobic interactions) that stabilize the protein's folded structure. Let’s analyze the options: - (A) There may be an increase in $\alpha$-helix and $\beta$-sheet structure: This statement is true. During denaturation, the protein unfolds and, in some cases, the random coil structure may lead to the formation of $\alpha$-helical or $\beta$-sheet regions. Denaturation doesn't necessarily cause complete loss of secondary structures but rather disrupts the native folding, which can lead to a change in the secondary structure. - (B) It is an irreversible process: This statement is incorrect. Denaturation is often reversible, especially when the denaturing agent is removed, and the protein can refold into its native structure. However, in some cases, denaturation can be irreversible if the protein is exposed to extreme conditions, such as high temperature or strong chemicals, which cause aggregation or covalent bond formation. - (C) When fully denatured, globular proteins resemble a random coil: This statement is true. When proteins are fully denatured, they lose their compact, globular structure and take on a random coil conformation. This is a characteristic feature of denatured proteins. - (D) The peptide bonds are broken: This statement is incorrect. Denaturation does not break the peptide bonds that link amino acids together. Peptide bonds remain intact, and only the protein's higher-order structures (secondary, tertiary, and quaternary structures) are disrupted. Thus, the correct answers are (A) and (C).